um: allow static linking for non-glibc libc implementations
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v4 cover um: allow static linking for non-glibc libc implementations
Changes from v3:
* restored FORBID_STATIC_LINK and renamed it to MAY_HAVE_RUNTIME_DEPS, so we don't have to maintain a static list of options, which may produce runtime dependencies
This is a continuation of [1]. Since I was able to produce a working UML binary with UML_NET_VECTOR linked with musl with the changes included in the patches here. I was compiling on Arch Linux, so hopefully all the latest versions of the compiler, libraries and binutils.
I also tested allyesconfig with both musl and glibc. The compilation succeeds with both, however both binaries (glibc one being dynamically linked) segfault on start. This is probably of some incompatible config option/module being included and not related to musl/glibc.
[1]: https://patchwork.ozlabs.org/project/linux-um/patch/[email protected]/
Ignat Korchagin (3):
um/kconfig: introduce CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS
um: some fixes to build UML with musl
um: allow static linking for non-glibc implementations
arch/um/Kconfig | 6 +++--- arch/um/drivers/Kconfig | 6 +++--- arch/um/drivers/daemon_user.c | 1 + arch/um/drivers/pcap_user.c | 12 ++++++------ arch/um/drivers/slip_user.c | 2 +- arch/um/drivers/vector_user.c | 4 +--- arch/um/os-Linux/util.c | 2 +- arch/x86/um/user-offsets.c | 2 +- init/Kconfig | 6 ++++++ scripts/cc-can-link.sh | 5 +++-- 10 files changed, 26 insertions(+), 20 deletions(-)
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PATCH v4 1/3 um/kconfig: introduce CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS
For statically linked UML build it is important to take into account the standard C-library implementation. Some implementations, notably glibc have
caveats: even when linked statically, the final program might require some runtime dependencies, if certain functions are used within the code.
Consider the following program:
int main(void)
{
getpwent();
return 0;
}Compiling this program and linking statically with glibc produces the following warning from the linker:/usr/sbin/ld: /tmp/ccuthw1o.o: in function `main':
test.c:(.text+0x5): warning: Using 'getpwent' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
We will use the flag to detect such C-library implementation build time and possibly disable static linking for UML to avoid producing a binary with unexpected behaviour and dependencies.
--- init/Kconfig | 6 ++++++ scripts/cc-can-link.sh | 5 +++-- 2 files changed, 9 insertions(+), 2 deletions(-)
init/Kconfig +6 -0
@@ -57,6 +57,12 @@ config CC_CAN_LINK_STATIC default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static) if 64BIT default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static) +config CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS + bool + depends on UML && CC_CAN_LINK_STATIC + default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static -Xlinker --fatal-warnings) if 64BIT + default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static -Xlinker --fatal-warnings) + config CC_HAS_ASM_GOTO def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
scripts/cc-can-link.sh +3 -2
@@ -2,10 +2,11 @@ # SPDX-License-Identifier: GPL-2.0 cat << "END" | $@ -x c - -o /dev/null >/dev/null 2>&1 -#include <stdio.h> +#include <sys/types.h> +#include <pwd.h> int main(void) { - printf(""); + getpwent(); return 0; } END
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2.20.1 _______________________________________________ linux-um mailing list [email protected] http://lists.infradead.org/mailman/listinfo/linux-um
PATCH v4 2/3 um: some fixes to build UML with musl
In reply to Ignat Korchaginmusl toolchain and headers are a bit more strict. These fixes enable building UML with musl as well as seem not to break on glibc.
--- arch/um/drivers/daemon_user.c | 1 + arch/um/drivers/pcap_user.c | 12 ++++++------ arch/um/drivers/slip_user.c | 2 +- arch/um/drivers/vector_user.c | 4 +--- arch/um/os-Linux/util.c | 2 +- arch/x86/um/user-offsets.c | 2 +- 6 files changed, 11 insertions(+), 12 deletions(-)
arch/um/drivers/daemon_user.c +1 -0
@@ -7,6 +7,7 @@*/ #include <stdint.h> +#include <string.h> #include <unistd.h> #include <errno.h> #include <sys/types.h>
arch/um/drivers/pcap_user.c +6 -6
@@ -32,7 +32,7 @@ static int pcap_user_init(void *data, void *dev)return 0 ; } -static int pcap_open (void *data) +static int pcap_user_open (void *data) {struct pcap_data *pri = data;__u32 netmask;
@@ -44,14 +44,14 @@ static int pcap_open(void *data)if (pri->filter !=NULL ) { err =dev_netmask (pri->dev, &netmask);if (err <0 ) { -printk (UM_KERN_ERR "pcap_open : dev_netmask failed\n" ); +printk (UM_KERN_ERR "pcap_user_open : dev_netmask failed\n" );return -EIO ; } pri->compiled =uml_kmalloc (sizeof (struct bpf_program ),UM_GFP_KERNEL );if (pri->compiled ==NULL ) { -printk (UM_KERN_ERR "pcap_open : kmalloc failed\n" ); +printk (UM_KERN_ERR "pcap_user_open : kmalloc failed\n" );return -ENOMEM ; }
@@ -59,14 +59,14 @@ static int pcap_open(void *data) (struct bpf_program *) pri->compiled, pri->filter, pri->optimize, netmask);if (err <0 ) { -printk (UM_KERN_ERR "pcap_open : pcap_compile failed - " +printk (UM_KERN_ERR "pcap_user_open : pcap_compile failed - " "'%s'\n" ,pcap_geterr (pri->pcap)); goto out; } err =pcap_setfilter (pri->pcap, pri->compiled);if (err <0 ) { -printk (UM_KERN_ERR "pcap_open : pcap_setfilter " +printk (UM_KERN_ERR "pcap_user_open : pcap_setfilter " "failed - '%s'\n" ,pcap_geterr (pri->pcap)); goto out; }
@@ -127,7 +127,7 @@ int pcap_user_read(int fd, void *buffer, int len, struct pcap_data *pri)const struct net_user_info pcap_user_info = { .init = pcap_user_init, - .open = pcap_open, + .open = pcap_user_open, .close =NULL , .remove = pcap_remove, .add_address =NULL ,
arch/um/drivers/slip_user.c +1 -1
@@ -9,7 +9,7 @@#include <errno.h> #include <fcntl.h> #include <string.h> -#include <sys/termios.h> +#include <termios.h> #include <sys/wait.h> #include <net_user.h> #include <os.h>
arch/um/drivers/vector_user.c +1 -3
@@ -18,9 +18,7 @@#include <fcntl.h> #include <sys/socket.h> #include <sys/un.h> -#include <net/ethernet.h> #include <netinet/ip.h> -#include <netinet/ether.h> #include <linux/if_ether.h> #include <linux/if_packet.h> #include <sys/wait.h>
@@ -332,7 +330,7 @@ static struct vector_fds *user_init_unix_fds(struct arglist *ifspec, int id) }switch (id) {case ID_BESS : -if (connect (fd, remote_addr,sizeof (struct sockaddr_un )) <0 ) { +if (connect (fd, (const struct sockaddr *) remote_addr,sizeof (struct sockaddr_un )) <0 ) {printk (UM_KERN_ERR "bess open:cannot connect to %s %i" , remote_addr->sun_path, -errno); goto unix_cleanup; }
arch/um/os-Linux/util.c +1 -1
@@ -10,7 +10,7 @@#include <signal.h> #include <string.h> #include <termios.h> -#include <wait.h> +#include <sys/wait.h> #include <sys/mman.h> #include <sys/utsname.h> #include <init.h>
arch/x86/um/user-offsets.c +1 -1
@@ -2,7 +2,7 @@#include <stdio.h> #include <stddef.h> #include <signal.h> -#include <sys/poll.h> +#include <poll.h> #include <sys/mman.h> #include <sys/user.h> #define __FRAME_OFFSETS
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PATCH v4 3/3 um: allow static linking for non-glibc implementations
In reply to Ignat KorchaginIt is possible to produce a statically linked UML binary with UML_NET_VECTOR, UML_NET_VDE and UML_NET_PCAP options enabled using alternative libc implementations, which do not rely on NSS, such as musl.
Allow static linking in this case.
--- arch/um/Kconfig | 6 +++--- arch/um/drivers/Kconfig | 6 +++--- 2 files changed, 6 insertions(+), 6 deletions(-)
arch/um/Kconfig +3 -3
@@ -62,12 +62,12 @@ config NR_CPUS source "arch/$(HEADER_ARCH)/um/Kconfig" -config FORBID_STATIC_LINK - bool +config MAY_HAVE_RUNTIME_DEPS + bool config STATIC_LINK bool "Force a static link" - depends on !FORBID_STATIC_LINK + depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS help This option gives you the ability to force a static link of UML. Normally, UML is linked as a shared binary. This is inconvenient for
arch/um/drivers/Kconfig +3 -3
@@ -234,7 +234,7 @@ config UML_NET_DAEMON config UML_NET_VECTOR bool "Vector I/O high performance network devices" depends on UML_NET - select FORBID_STATIC_LINK + select MAY_HAVE_RUNTIME_DEPS help This User-Mode Linux network driver uses multi-message send and receive functions. The host running the UML guest must have
@@ -246,7 +246,7 @@ config UML_NET_VECTOR config UML_NET_VDE bool "VDE transport (obsolete)" depends on UML_NET - select FORBID_STATIC_LINK + select MAY_HAVE_RUNTIME_DEPS help This User-Mode Linux network transport allows one or more running UMLs on a single host to communicate with each other and also
@@ -294,7 +294,7 @@ config UML_NET_MCAST config UML_NET_PCAP bool "pcap transport (obsolete)" depends on UML_NET - select FORBID_STATIC_LINK + select MAY_HAVE_RUNTIME_DEPS help The pcap transport makes a pcap packet stream on the host look like an ethernet device inside UML. This is useful for making
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