kexec_load manpage
Subsystems (3)
PATCH 1/1 kexec_load manpage
Here are the beginnings of a kexec_load manpage.
Probably needs some more review from Eric and may need some additional information.
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
Also added the kexec subcall to reboot(2)
-Andi
man2/kexec_load.2 new file +94 -0
@@ -0,0 +1,94 @@ +.TH KEXEC_LOAD 2 2010-06-16 "Linux" "Linux Programmer's Manual" +.SH NAME +kexec_load \- Load a new kernel for later execution. +.SH SYNOPSIS +.b #include <linux/kexec.h> +.br +.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments "," +.br +.BI "struct kexec_segment *" segments ", unsigned long " flags ");" +.SH DESCRIPTION +.BR kexec_load +loads a new kernel that can be executed later +by +.I reboot(2). +An alternative approach is to specify +.B KEXEC_ON_CRASH +in the +.I flags +argument and then the new kernel will be automatically executed on a +system crash. +.\" XXX figure out how this is really used +With +.B KEXEC_PRESERVE_CONTEXT +specified in +.I flags +kexec will preserve the system hard and +software state before executing the kexec kernel. This +could be used for system suspend. + +.I flags +also contains the architecture of the executed kernel or +be +.I KEXEC_ARCH_DEFAULT +for the current architecture. +Valid architectures are +.I KEXEC_ARCH_I386, +.I KEXEC_ARCH_X86_64, +.I KEXEC_ARCH_PPC, +.I KEXEC_ARCH_PPC64, +.I KEXEC_ARCH_IA_64, +.I KEXEC_ARCH_ARM, +.I KEXEC_ARCH_S390, +.I KEXEC_ARCH_SH, +.I KEXEC_ARCH_MIPS, +.I KEXEC_ARCH_MIPS_LE. +The architecture must be executable on the CPU of the system. + +.I entry +is the virtual entry address in the kernel image. +.I nr_segments +is the number of segments pointed to by the +.I segments +pointer. +.I segments +is an array of +.I struct kexec_segment +structures which define the kernel layout: +.in +4n +.nf + +struct kexec_segment { + void *buf; /* Buffer in user space */ + size_t bufsz; /* Buffer length in user space */ + void *mem; /* Virtual address of kernel */ + size_t memsz; /* Virtual address length */ +}; +.fi +.in +.PP +.\" XXX elaborate on this +The kernel image defined by +.I segments +is copied from the calling process into previously reserved memory. +.SH CONFORMING TO +This system call is Linux-specific. +.SH NOTES +kexec_load is currently not defined in glibc. To call it use: +.in +4n +.nf +#define _GNU_SOURCE +#include <syscall.h> +#include <asm/unistd.h> +#include <linux/kexec.h> + +ret = syscall(__NR_kexec_load, entry, nr_segments, segments, flags); +.fi +.in +.PP +.I linux/kexec.h as a exported header is only available in 2.6.38 +and later kernels, in earlier kernels the constants need to be copied +out of the kernel source. +.SH SEE ALSO +.BR syscall (2), +.BR reboot (2)
man2/reboot.2 +7 -1
@@ -139,6 +139,11 @@ For the i386 architecture, the additional argument does not do anything at present (2.1.122), but the type of reboot can be determined by kernel command-line arguments ("reboot=...") to be either warm or cold, and either hard or through the BIOS. +.TP +.B LINUX_REBOOT_KEXEC +executes a kernel that has been loaded earlier +with +.I kexec_load(2). .SH "RETURN VALUE" For the values of .I cmd
@@ -177,4 +182,5 @@ and should not be used in programs intended to be portable. .BR capabilities (7), .BR ctrlaltdel (8), .BR halt (8), -.BR reboot (8) +.BR reboot (8), +.BR kexec_load (2)
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Quoted 7 lines · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.Probably needs some more review from Eric and may need some additional information.
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
The syscall has been used for years with a separate non-kernel header.
Eric
Quoted 49 lines
Also added the kexec subcall to reboot(2)
(quoted diff) +0
-1-Andiman2/kexec_load.2 new file +39
-0@@ -0,0 +1,94 @@ +.TH KEXEC_LOAD 2 2010-06-16 "Linux" "Linux Programmer's Manual" +.SH NAME +kexec_load \- Load a new kernel for later execution. +.SH SYNOPSIS +.b #include <linux/kexec.h> +.br +.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments "," +.br +.BI "struct kexec_segment *" segments ", unsigned long " flags ");" +.SH DESCRIPTION +.BR kexec_load +loads a new kernel that can be executed later +by +.I reboot(2). +An alternative approach is to specify +.B KEXEC_ON_CRASH +in the +.I flags +argument and then the new kernel will be automatically executed on a +system crash. +.\" XXX figure out how this is really used +With +.B KEXEC_PRESERVE_CONTEXT +specified in +.I flags +kexec will preserve the system hard and +software state before executing the kexec kernel. This +could be used for system suspend. + +.I flags +also contains the architecture of the executed kernel or +be +.I KEXEC_ARCH_DEFAULT +for the current architecture. +Valid architectures are +.I KEXEC_ARCH_I386, +.I KEXEC_ARCH_X86_64, +.I KEXEC_ARCH_PPC, +.I KEXEC_ARCH_PPC64,
man2/kexec_load.2 line 49
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I KEXEC_ARCH_IA_64, +.I KEXEC_ARCH_ARM, +.I KEXEC_ARCH_S390, +.I KEXEC_ARCH_SH, +.I KEXEC_ARCH_MIPS, +.I KEXEC_ARCH_MIPS_LE. +The architecture must be executable on the CPU of the system. + +.I entry +is the virtual entry address in the kernel image.
Physical.
Quoted 6 lines
man2/kexec_load.2 new file +6
-0+.I nr_segments +is the number of segments pointed to by the +.I segments +pointer. +.I segments +is an array of
man2/kexec_load.2 line 65
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I struct kexec_segment +structures which define the kernel layout: +.in +4n +.nf + +struct kexec_segment { + void *buf; /* Buffer in user space */ + size_t bufsz; /* Buffer length in user space */ + void *mem; /* Virtual address of kernel */ + size_t memsz; /* Virtual address length */
There are again physical addresses.
There is an expectation that at hand off from sys_kexec that virtual and physical addresses will be identity mapped. But this isn't the old Alpha booting convention where you have a virtual address and then you have to parse the page table to figure out where your kernel was actually loaded.
Quoted 46 lines
man2/kexec_load.2 new file +29
-0+}; +.fi +.in +.PP +.\" XXX elaborate on this +The kernel image defined by +.I segments +is copied from the calling process into previously reserved memory. +.SH CONFORMING TO +This system call is Linux-specific. +.SH NOTES +kexec_load is currently not defined in glibc. To call it use: +.in +4n +.nf +#define _GNU_SOURCE +#include <syscall.h> +#include <asm/unistd.h> +#include <linux/kexec.h> + +ret = syscall(__NR_kexec_load, entry, nr_segments, segments, flags); +.fi +.in +.PP +.I linux/kexec.h as a exported header is only available in 2.6.38 +and later kernels, in earlier kernels the constants need to be copied +out of the kernel source. +.SH SEE ALSO +.BR syscall (2), +.BR reboot (2)man2/reboot.2 +5
-0@@ -139,6 +139,11 @@ For the i386 architecture, the additional argument does not do anything at present (2.1.122), but the type of reboot can be determined by kernel command-line arguments ("reboot=...") to be either warm or cold, and either hard or through the BIOS. +.TP +.B LINUX_REBOOT_KEXEC +executes a kernel that has been loaded earlier +with +.I kexec_load(2). .SH "RETURN VALUE" For the values of .I cmd
man2/reboot.2 and should not be used in programs intended to be portable. · line 186
Quoted 6 lines
man2/reboot.2 +2
-1@@ -177,4 +182,5 @@ and should not be used in programs intended to be portable. .BR capabilities (7), .BR ctrlaltdel (8), .BR halt (8), -.BR reboot (8) +.BR reboot (8), +.BR kexec_load (2)
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Quoted 11 lines · Eric W. Biederman
Quoted 7 lines · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.Probably needs some more review from Eric and may need some additional information.
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
The syscall has been used for years with a separate non-kernel header.
Yes but that's not a sane interface that can be documented.
-Andi
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Quoted 8 lines · Andi Kleen
Quoted 7 lines · Eric W. Biederman
Quoted 5 lines · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.Probably needs some more review from Eric and may need some additional information.
Quoted 6 lines
Quoted 4 lines
Quoted 2 lines
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
The syscall has been used for years with a separate non-kernel header.
Yes but that's not a sane interface that can be documented.
Agreed. Surely the right thing to do is export the proper header?
Thanks,
Michael
Signature · 7 lines
Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
Quoted 9 lines · Michael Kerrisk
Quoted 8 lines · Andi Kleen
Quoted 7 lines · Eric W. Biederman
Quoted 5 lines · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.Probably needs some more review from Eric and may need some additional information.
Quoted 8 lines
Quoted 6 lines
Quoted 4 lines
Quoted 2 lines
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
The syscall has been used for years with a separate non-kernel header.
Yes but that's not a sane interface that can be documented.
Agreed. Surely the right thing to do is export the proper header?
I am in favour of that option.
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Andi,
Are Eric's suggestions of "physical" below correct? If so, could you amend the page and resubmit?
Also, I'd prefer to have the reboot.2 and kexec_load.2 page as separate patches, so could you split them on the resend please?
Thanks,
Michael
Quoted 156 lines · Eric W. Biederman
Quoted 7 lines · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.Probably needs some more review from Eric and may need some additional information.
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
The syscall has been used for years with a separate non-kernel header.
Eric
Quoted 49 lines
Also added the kexec subcall to reboot(2)
(quoted diff) +0
-1-Andiman2/kexec_load.2 new file +39
-0@@ -0,0 +1,94 @@ +.TH KEXEC_LOAD 2 2010-06-16 "Linux" "Linux Programmer's Manual" +.SH NAME +kexec_load \- Load a new kernel for later execution. +.SH SYNOPSIS +.b #include <linux/kexec.h> +.br +.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments "," +.br +.BI "struct kexec_segment *" segments ", unsigned long " flags ");" +.SH DESCRIPTION +.BR kexec_load +loads a new kernel that can be executed later +by +.I reboot(2). +An alternative approach is to specify +.B KEXEC_ON_CRASH +in the +.I flags +argument and then the new kernel will be automatically executed on a +system crash. +.\" XXX figure out how this is really used +With +.B KEXEC_PRESERVE_CONTEXT +specified in +.I flags +kexec will preserve the system hard and +software state before executing the kexec kernel. This +could be used for system suspend. + +.I flags +also contains the architecture of the executed kernel or +be +.I KEXEC_ARCH_DEFAULT +for the current architecture. +Valid architectures are +.I KEXEC_ARCH_I386, +.I KEXEC_ARCH_X86_64, +.I KEXEC_ARCH_PPC, +.I KEXEC_ARCH_PPC64,man2/kexec_load.2 line 49
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I KEXEC_ARCH_IA_64, +.I KEXEC_ARCH_ARM, +.I KEXEC_ARCH_S390, +.I KEXEC_ARCH_SH, +.I KEXEC_ARCH_MIPS, +.I KEXEC_ARCH_MIPS_LE. +The architecture must be executable on the CPU of the system. + +.I entry +is the virtual entry address in the kernel image.Physical.
Quoted 6 lines
man2/kexec_load.2 new file +6
-0+.I nr_segments +is the number of segments pointed to by the +.I segments +pointer. +.I segments +is an array ofman2/kexec_load.2 line 65
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I struct kexec_segment +structures which define the kernel layout: +.in +4n +.nf + +struct kexec_segment { + void *buf; /* Buffer in user space */ + size_t bufsz; /* Buffer length in user space */ + void *mem; /* Virtual address of kernel */ + size_t memsz; /* Virtual address length */There are again physical addresses.
There is an expectation that at hand off from
sys_kexecthat virtual and physical addresses will be identity mapped. But this isn't the old Alpha booting convention where you have a virtual address and then you have to parse the page table to figure out where your kernel was actually loaded.Quoted 52 lines
man2/kexec_load.2 new file +29
-0+}; +.fi +.in +.PP +.\" XXX elaborate on this +The kernel image defined by +.I segments +is copied from the calling process into previously reserved memory. +.SH CONFORMING TO +This system call is Linux-specific. +.SH NOTES +kexec_load is currently not defined in glibc. To call it use: +.in +4n +.nf +#define _GNU_SOURCE +#include <syscall.h> +#include <asm/unistd.h> +#include <linux/kexec.h> + +ret = syscall(__NR_kexec_load, entry, nr_segments, segments, flags); +.fi +.in +.PP +.I linux/kexec.h as a exported header is only available in 2.6.38 +and later kernels, in earlier kernels the constants need to be copied +out of the kernel source. +.SH SEE ALSO +.BR syscall (2), +.BR reboot (2)man2/reboot.2 +0
-0@@ -139,6 +139,11 @@ For the i386 architecture, the additional argument does not doanything at present (2.1.122), but the type of reboot can be determined by kernel command-line arguments ("reboot=...") to be either warm or cold, and either hard or through the BIOS. +.TP
+.BLINUX_REBOOT_KEXECman2/reboot.2 +3
-0+executes a kernel that has been loaded earlier +with +.I kexec_load(2)..SH "RETURN VALUE"
For the values of
.I cmdman2/reboot.2 +2
-1@@ -177,4 +182,5 @@ and should not be used in programs intended to be portable. .BR capabilities (7), .BR ctrlaltdel (8), .BR halt (8), -.BR reboot (8) +.BR reboot (8), +.BR kexec_load (2)
Signature · 7 lines
Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface" http://blog.man7.org/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Andi,
Ping!
Cheers,
Michael
Quoted 178 lines · Michael Kerrisk
Hi Andi,
Are Eric's suggestions of "physical" below correct? If so, could you amend the page and resubmit?
Also, I'd prefer to have the reboot.2 and kexec_load.2 page as separate patches, so could you split them on the resend please?
Thanks,
Michael
Quoted 147 lines · Eric W. Biederman
Quoted 7 lines · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.Probably needs some more review from Eric and may need some additional information.
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
The syscall has been used for years with a separate non-kernel header.
Eric
Quoted 49 lines
Also added the kexec subcall to reboot(2)
(quoted diff) +0
-1-Andiman2/kexec_load.2 new file +39
-0@@ -0,0 +1,94 @@ +.TH KEXEC_LOAD 2 2010-06-16 "Linux" "Linux Programmer's Manual" +.SH NAME +kexec_load \- Load a new kernel for later execution. +.SH SYNOPSIS +.b #include <linux/kexec.h> +.br +.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments "," +.br +.BI "struct kexec_segment *" segments ", unsigned long " flags ");" +.SH DESCRIPTION +.BR kexec_load +loads a new kernel that can be executed later +by +.I reboot(2). +An alternative approach is to specify +.B KEXEC_ON_CRASH +in the +.I flags +argument and then the new kernel will be automatically executed on a +system crash. +.\" XXX figure out how this is really used +With +.B KEXEC_PRESERVE_CONTEXT +specified in +.I flags +kexec will preserve the system hard and +software state before executing the kexec kernel. This +could be used for system suspend. + +.I flags +also contains the architecture of the executed kernel or +be +.I KEXEC_ARCH_DEFAULT +for the current architecture. +Valid architectures are +.I KEXEC_ARCH_I386, +.I KEXEC_ARCH_X86_64, +.I KEXEC_ARCH_PPC, +.I KEXEC_ARCH_PPC64,man2/kexec_load.2 line 49
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I KEXEC_ARCH_IA_64, +.I KEXEC_ARCH_ARM, +.I KEXEC_ARCH_S390, +.I KEXEC_ARCH_SH, +.I KEXEC_ARCH_MIPS, +.I KEXEC_ARCH_MIPS_LE. +The architecture must be executable on the CPU of the system. + +.I entry +is the virtual entry address in the kernel image.Physical.
Quoted 6 lines
man2/kexec_load.2 new file +6
-0+.I nr_segments +is the number of segments pointed to by the +.I segments +pointer. +.I segments +is an array ofman2/kexec_load.2 line 65
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I struct kexec_segment +structures which define the kernel layout: +.in +4n +.nf + +struct kexec_segment { + void *buf; /* Buffer in user space */ + size_t bufsz; /* Buffer length in user space */ + void *mem; /* Virtual address of kernel */ + size_t memsz; /* Virtual address length */There are again physical addresses.
There is an expectation that at hand off from
sys_kexecthat virtual and physical addresses will be identity mapped. But this isn't the old Alpha booting convention where you have a virtual address and then you have to parse the page table to figure out where your kernel was actually loaded.Quoted 44 lines
man2/kexec_load.2 new file +29
-0+}; +.fi +.in +.PP +.\" XXX elaborate on this +The kernel image defined by +.I segments +is copied from the calling process into previously reserved memory. +.SH CONFORMING TO +This system call is Linux-specific. +.SH NOTES +kexec_load is currently not defined in glibc. To call it use: +.in +4n +.nf +#define _GNU_SOURCE +#include <syscall.h> +#include <asm/unistd.h> +#include <linux/kexec.h> + +ret = syscall(__NR_kexec_load, entry, nr_segments, segments, flags); +.fi +.in +.PP +.I linux/kexec.h as a exported header is only available in 2.6.38 +and later kernels, in earlier kernels the constants need to be copied +out of the kernel source. +.SH SEE ALSO +.BR syscall (2), +.BR reboot (2)man2/reboot.2 +0
-0@@ -139,6 +139,11 @@ For the i386 architecture, the additional argument does not doanything at present (2.1.122), but the type of reboot can be determined by kernel command-line arguments ("reboot=...") to be either warm or cold, and either hard or through the BIOS. +.TP
+.BLINUX_REBOOT_KEXECman2/reboot.2 +3
-0+executes a kernel that has been loaded earlier +with +.I kexec_load(2)..SH "RETURN VALUE"
For the values ofQuoted 9 lines
man2/reboot.2 and should not be used in programs intended to be portable. · line 186
Quoted 8 lines
.I cmd
man2/reboot.2 +2
-1@@ -177,4 +182,5 @@ and should not be used in programs intended to be portable. .BR capabilities (7), .BR ctrlaltdel (8), .BR halt (8), -.BR reboot (8) +.BR reboot (8), +.BR kexec_load (2)--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface" http://blog.man7.org/
Signature · 7 lines
Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
Hey Andi,
I'd like to push this page out the door, but I'm blocked doing so until I hear back from you regarding the question below (plus a new version of the page, if needed please).
Thanks,
Michael
Quoted 196 lines · Michael Kerrisk
Hi Andi,
Ping!
Cheers,
Michael
Quoted 173 lines · Michael Kerrisk
Hi Andi,
Are Eric's suggestions of "physical" below correct? If so, could you amend the page and resubmit?
Also, I'd prefer to have the reboot.2 and kexec_load.2 page as separate patches, so could you split them on the resend please?
Thanks,
Michael
Quoted 147 lines · Eric W. Biederman
Quoted 7 lines · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.Probably needs some more review from Eric and may need some additional information.
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
The syscall has been used for years with a separate non-kernel header.
Eric
Quoted 49 lines
Also added the kexec subcall to reboot(2)
(quoted diff) +0
-1-Andiman2/kexec_load.2 new file +39
-0@@ -0,0 +1,94 @@ +.TH KEXEC_LOAD 2 2010-06-16 "Linux" "Linux Programmer's Manual" +.SH NAME +kexec_load \- Load a new kernel for later execution. +.SH SYNOPSIS +.b #include <linux/kexec.h> +.br +.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments "," +.br +.BI "struct kexec_segment *" segments ", unsigned long " flags ");" +.SH DESCRIPTION +.BR kexec_load +loads a new kernel that can be executed later +by +.I reboot(2). +An alternative approach is to specify +.B KEXEC_ON_CRASH +in the +.I flags +argument and then the new kernel will be automatically executed on a +system crash. +.\" XXX figure out how this is really used +With +.B KEXEC_PRESERVE_CONTEXT +specified in +.I flags +kexec will preserve the system hard and +software state before executing the kexec kernel. This +could be used for system suspend. + +.I flags +also contains the architecture of the executed kernel or +be +.I KEXEC_ARCH_DEFAULT +for the current architecture. +Valid architectures are +.I KEXEC_ARCH_I386, +.I KEXEC_ARCH_X86_64, +.I KEXEC_ARCH_PPC, +.I KEXEC_ARCH_PPC64,man2/kexec_load.2 line 49
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I KEXEC_ARCH_IA_64, +.I KEXEC_ARCH_ARM, +.I KEXEC_ARCH_S390, +.I KEXEC_ARCH_SH, +.I KEXEC_ARCH_MIPS, +.I KEXEC_ARCH_MIPS_LE. +The architecture must be executable on the CPU of the system. + +.I entry +is the virtual entry address in the kernel image.Physical.
Quoted 6 lines
man2/kexec_load.2 new file +6
-0+.I nr_segments +is the number of segments pointed to by the +.I segments +pointer. +.I segments +is an array ofman2/kexec_load.2 line 65
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I struct kexec_segment +structures which define the kernel layout: +.in +4n +.nf + +struct kexec_segment { + void *buf; /* Buffer in user space */ + size_t bufsz; /* Buffer length in user space */ + void *mem; /* Virtual address of kernel */ + size_t memsz; /* Virtual address length */There are again physical addresses.
There is an expectation that at hand off from
sys_kexecthat virtual and physical addresses will be identity mapped. But this isn't the old Alpha booting convention where you have a virtual address and then you have to parse the page table to figure out where your kernel was actually loaded.Quoted 44 lines
man2/kexec_load.2 new file +29
-0+}; +.fi +.in +.PP +.\" XXX elaborate on this +The kernel image defined by +.I segments +is copied from the calling process into previously reserved memory. +.SH CONFORMING TO +This system call is Linux-specific. +.SH NOTES +kexec_load is currently not defined in glibc. To call it use: +.in +4n +.nf +#define _GNU_SOURCE +#include <syscall.h> +#include <asm/unistd.h> +#include <linux/kexec.h> + +ret = syscall(__NR_kexec_load, entry, nr_segments, segments, flags); +.fi +.in +.PP +.I linux/kexec.h as a exported header is only available in 2.6.38 +and later kernels, in earlier kernels the constants need to be copied +out of the kernel source. +.SH SEE ALSO +.BR syscall (2), +.BR reboot (2)man2/reboot.2 +0
-0@@ -139,6 +139,11 @@ For the i386 architecture, the additional argument does not doanything at present (2.1.122), but the type of reboot can be determined by kernel command-line arguments ("reboot=...") to be either warm or cold, and either hard or through the BIOS. +.TP
+.BLINUX_REBOOT_KEXECman2/reboot.2 +3
-0+executes a kernel that has been loaded earlier +with +.I kexec_load(2)..SH "RETURN VALUE"
For the values ofQuoted 9 lines
man2/reboot.2 and should not be used in programs intended to be portable. · line 186
Quoted 8 lines
.I cmd
man2/reboot.2 +2
-1@@ -177,4 +182,5 @@ and should not be used in programs intended to be portable. .BR capabilities (7), .BR ctrlaltdel (8), .BR halt (8), -.BR reboot (8) +.BR reboot (8), +.BR kexec_load (2)Quoted 5 lines
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface" http://blog.man7.org/--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface"; http://man7.org/tlpi/
Signature · 7 lines
Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
Quoted 5 lines · Michael Kerrisk
Hey Andi,
I'd like to push this page out the door, but I'm blocked doing so until I hear back from you regarding the question below (plus a new version of the page, if needed please).
Probably. Eric should know.
Frankly without an header the syscall is pretty much unusable for normal programs anyways, so I gave up on this.
-Andi
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Quoted 11 lines · Andi Kleen
Quoted 5 lines · Michael Kerrisk
Hey Andi,
I'd like to push this page out the door, but I'm blocked doing so until I hear back from you regarding the question below (plus a new version of the page, if needed please).
Probably. Eric should know.
Frankly without an header the syscall is pretty much unusable for normal programs anyways, so I gave up on this.
I'm not sure that I ever understood the impasse over the header.
_______________________________________________
kexec mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/kexec
Quoted 8 lines · Simon Horman
Quoted 7 lines · Andi Kleen
Quoted 5 lines · Michael Kerrisk
Hey Andi,
I'd like to push this page out the door, but I'm blocked doing so until I hear back from you regarding the question below (plus a new version of the page, if needed please).
Quoted 6 lines
Quoted 4 lines
Probably. Eric should know.
Frankly without an header the syscall is pretty much unusable for normal programs anyways, so I gave up on this.
I'm not sure that I ever understood the impasse over the header.
It's basically: should kexec_load only be used from kexec(8) or is it a generally available syscall.
If the former is true no header or manpage is needed. For the later both are.
-Andi
Signature · 5 lines
ak-VuQAYsv1563Yd54FQh9/[email protected] -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
Quoted 14 lines · Andi Kleen
Quoted 13 lines · Simon Horman
Quoted 11 lines · Andi Kleen
Quoted 5 lines · Michael Kerrisk
Hey Andi,
I'd like to push this page out the door, but I'm blocked doing so until I hear back from you regarding the question below (plus a new version of the page, if needed please).
Probably. Eric should know.
Frankly without an header the syscall is pretty much unusable for normal programs anyways, so I gave up on this.
Quoted 7 lines
Quoted 1 line
I'm not sure that I ever understood the impasse over the header.
It's basically: should
kexec_loadonly be used from kexec(8) or is it a generally available syscall.If the former is true no header or manpage is needed. For the later both are.
Magnus Damm is interested in having a kexec-tools module for busybox [1]. And I suspect that would be somewhat less tedious to implement if kexec was a generally available syscall.
[1] http://tree.celinuxforum.org/pipermail/celinux-dev/2010-October/002057.html
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Andi, Erric, and all,
Quoted 14 lines · Andi Kleen
Quoted 13 lines · Simon Horman
Quoted 11 lines · Andi Kleen
Quoted 5 lines · Michael Kerrisk
Hey Andi,
I'd like to push this page out the door, but I'm blocked doing so until I hear back from you regarding the question below (plus a new version of the page, if needed please).
Probably. Eric should know.
Frankly without an header the syscall is pretty much unusable for normal programs anyways, so I gave up on this.
Quoted 7 lines
Quoted 1 line
I'm not sure that I ever understood the impasse over the header.
It's basically: should
kexec_loadonly be used from kexec(8) or is it a generally available syscall.If the former is true no header or manpage is needed. For the later both are.
On the other hand, I always think a man page is needed...
Andi, I incorporated Eric's suggestions and made a few other changes:
Added a license (Andi, I used the verbatim license, and put copyright in your name -- okay?)
Various wording and layout improvements.
Fixed the name of a constant: s/KEXEC_ARCH_I386/KEXEC_ARCH_386/.
Added RETURN VALUE and ERRORS sections.
Added VERSIONS section
Removed details of using syscall; the reader can find them in syscall(2).
Added some details for KEXEC_PRESERVE_CONTEXT.
Revised the text mentioning the kernel header, since it is not yet exported, and it's not certain that it will be.
Note that CONFIG_KEXEC is needed
Review of my changes, and of course Andi's original would be most welcome. The current version of the page is pushed to git, and inline below.
Cheers,
Michael
.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright (C) 2010 Andi Kleen
.\"
.\" Permission is granted to make and distribute verbatim copies of this .\" manual provided the copyright notice and this permission notice are .\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this .\" manual under the conditions for verbatim copying, provided that the .\" entire resulting derived work is distributed under the terms of a .\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this .\" manual page may be incorrect or out-of-date. The author(s) assume no .\" responsibility for errors or omissions, or for damages resulting from .\" the use of the information contained herein. The author(s) may not .\" have taken the same level of care in the production of this manual, .\" which is licensed free of charge, as they might when working .\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by .\" the source, must acknowledge the copyright and authors of this work. .TH KEXEC_LOAD 2 2010-10-31 "Linux" "Linux Programmer's Manual" .SH NAMEkexec_load \- load a new kernel for later execution
.SH SYNOPSIS
.b #include <linux/kexec.h>
.br
.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments "," .br
.BI " struct kexec_segment *" segments \
", unsigned long " flags ");"
.SH DESCRIPTION
The
.BR kexec_load ()
system call loads a new kernel that can be executed later by
.BR reboot(2) .
.PP
The
.I flags
argument is a mask whose high-order bits control the operation of the call. The following values can be specified in
.IR flags :
.TP
.B KEXEC_ON_CRASH
Execute the new kernel automatically on a system crash.
.\" FIXME figure out how this is really used
.TP
.B KEXEC_PRESERVE_CONTEXT
Preserve the system hardware and
software states before executing the new kernel.
This could be used for system suspend.
This flag is only available if the kernel was configured with
.BR CONFIG_KEXEC_JUMP ,
and is only effective if
.I nr_segments
is greater than 0.
.PP
The low-order bits of
.I flags
contain the architecture of the to-be-executed kernel.
Specify (OR) the constant
.B KEXEC_ARCH_DEFAULT
to use the current architecture,
or one of the following architecture constants
.BR KEXEC_ARCH_386 ,
.BR KEXEC_ARCH_X86_64 ,
.BR KEXEC_ARCH_PPC ,
.BR KEXEC_ARCH_PPC64 ,
.BR KEXEC_ARCH_IA_64 ,
.BR KEXEC_ARCH_ARM ,
.BR KEXEC_ARCH_S390 ,
.BR KEXEC_ARCH_SH ,
.BR KEXEC_ARCH_MIPS ,
and
.BR KEXEC_ARCH_MIPS_LE .
The architecture must be executable on the CPU of the system.
The
.I entry
argument is the physical entry address in the kernel image. The
.I nr_segments
argument is the number of segments pointed to by the .I segments
pointer.
The
.I segments
argument is an array of
.I kexec_segment
structures which define the kernel layout:
.in +4n
.nf
struct kexec_segment {
void *buf; /* Buffer in user space */
size_t bufsz; /* Buffer length in user space */
void *mem; /* Physical address of kernel */
size_t memsz; /* Physical address length */};
.fi
.in
.PP
.\" FIXME elaborate on the following:
The kernel image defined by
.I segments
is copied from the calling process into previously reserved memory. .SH RETURN VALUE
On success,
.BR kexec_load ()
returns 0.
On error, -1 is returned and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EBUSY
Another crash kernel is already being loaded
or a crash kernel is already in use.
.TP
.B EINVAL
.I flags
is invalid; of
.IR nr_segments is too large
.\" KEXEC_SEGMENT_MAX == 16
.TP
.B EPERM
The caller does not have the
.BR CAP_SYS_BOOT
capability.
.SH VERSIONS
The
.BR kexec_load ()
system call first appeared in Linux 2.6.7.
.SH CONFORMING TO
This system call is Linux-specific.
.SH NOTES
Currently, there is no glibc support for
.BR kexec_load ().
Call it using
.BR syscall (2).
.PP
The required constants are in the kernel source file
.IR linux/kexec.h ,
which is not currently exported to glibc.
.\" FIXME Andi submitted a patch for this.
.\" Check if it got accepted later.
Therefore, these constants must be defined manually.
This system call is only available if the kernel was configured with .BR CONFIG_KEXEC .
.SH SEE ALSO
.BR syscall (2),
.BR reboot (2)
Signature · 7 lines
Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello Eric,
Quoted 69 lines · Eric W. Biederman
Quoted 7 lines · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.Probably needs some more review from Eric and may need some additional information.
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
The syscall has been used for years with a separate non-kernel header.
Eric
Quoted 53 lines
Also added the kexec subcall to reboot(2)
(quoted diff) +0
-1-Andiman2/kexec_load.2 new file +43
-0@@ -0,0 +1,94 @@ +.TH KEXEC_LOAD 2 2010-06-16 "Linux" "Linux Programmer's Manual" +.SH NAME +kexec_load \- Load a new kernel for later execution. +.SH SYNOPSIS +.b #include <linux/kexec.h> +.br +.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments "," +.br +.BI "struct kexec_segment *" segments ", unsigned long " flags ");" +.SH DESCRIPTION +.BR kexec_load +loads a new kernel that can be executed later +by +.I reboot(2). +An alternative approach is to specify +.B KEXEC_ON_CRASH +in the +.I flags +argument and then the new kernel will be automatically executed on a +system crash. +.\" XXX figure out how this is really used +With +.B KEXEC_PRESERVE_CONTEXT +specified in +.I flags +kexec will preserve the system hard and +software state before executing the kexec kernel. This +could be used for system suspend. + +.I flags +also contains the architecture of the executed kernel or +be +.I KEXEC_ARCH_DEFAULT +for the current architecture. +Valid architectures are +.I KEXEC_ARCH_I386, +.I KEXEC_ARCH_X86_64, +.I KEXEC_ARCH_PPC, +.I KEXEC_ARCH_PPC64, +.I KEXEC_ARCH_IA_64, +.I KEXEC_ARCH_ARM, +.I KEXEC_ARCH_S390, +.I KEXEC_ARCH_SH,
Quoted 8 lines
man2/kexec_load.2 line 49
Quoted 6 lines
man2/kexec_load.2 new file +6
-0+.I KEXEC_ARCH_MIPS, +.I KEXEC_ARCH_MIPS_LE. +The architecture must be executable on the CPU of the system. + +.I entry +is the virtual entry address in the kernel image.Physical.
Changed.
Quoted 10 lines
Quoted 10 lines
man2/kexec_load.2 new file +10
-0+.I nr_segments +is the number of segments pointed to by the +.I segments +pointer. +.I segments +is an array of +.I struct kexec_segment +structures which define the kernel layout: +.in +4n +.nf
Quoted 8 lines
man2/kexec_load.2 line 65
Quoted 6 lines
man2/kexec_load.2 new file +6
-0+ +struct kexec_segment { + void *buf; /* Buffer in user space */ + size_t bufsz; /* Buffer length in user space */ + void *mem; /* Virtual address of kernel */ + size_t memsz; /* Virtual address length */There are again physical addresses.
Changed.
Thanks,
Michael
Quoted 5 lines
There is an expectation that at hand off from
sys_kexecthat virtual and physical addresses will be identity mapped. But this isn't the old Alpha booting convention where you have a virtual address and then you have to parse the page table to figure out where your kernel was actually loaded.
Signature · 7 lines
Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
A message that is not in the archive (sent off-list or not yet received): 20100619132633.GA24277-u0/[email protected]
Michael Kerrisk
AppliedHi Andi,
Quoted 1 line · Andi Kleen
Here are the beginnings of a
kexec_loadmanpage.
Thanks. I have added this page to the set. In another reply, I'll show some revisions I made to the page.
Quoted 2 lines
Probably needs some more review from Eric and may need some additional information.
I will pull Eric's comments into the page.
Quoted 2 lines
The syscall is actually only usable with a kernel patch to export the header I just sent separately.
Will this patch make it in?
Quoted 1 line
Also added the kexec subcall to reboot(2)
Applied.
The changes will be in man-pages 3.30.
Thanks,
Michael
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