EFI Boot Stub Early Console
Hello,
How do I get the early boot console to show up on my screen when booting with the EFI boot stub? I can see it through the serial port if I set console=tty0, and I see the second half of the boot sequence after my initrd loads fbcon, but the screen remains unchanging until then. I'm using 3.3-rc7 on Virtualbox's EFI implementation.
Thanks,
Shea
Quoted 1 line · Shea Levy
console=tty0
Sorry, that should have been console=ttyS0
Quoted 4 lines · Shea Levy
Quoted 1 line · Shea Levy
console=tty0
Sorry, that should have been console=ttyS0
Have you tried earlyprintk=serial,ttyS0?
-hpa
Quoted 8 lines · H. Peter Anvin
Quoted 3 lines · Shea Levy
Quoted 1 line · Shea Levy
console=tty0
Sorry, that should have been console=ttyS0
Have you tried earlyprintk=serial,ttyS0?
-hpa
Just tried. Still nothing in the VirtualBox window, serial port showed boot output up until "[ 0.000000] console [tty0] enabled, bootconsole disabled", when the rest of the boot process happened in VirtualBox.
~Shea
Quoted 5 lines · Shea Levy
Quoted 4 lines · H. Peter Anvin
Quoted 3 lines · Shea Levy
Quoted 1 line · Shea Levy
console=tty0
Sorry, that should have been console=ttyS0
Quoted 9 lines
Quoted 4 lines
Have you tried earlyprintk=serial,ttyS0?
-hpa
Just tried. Still nothing in the VirtualBox window, serial port showed
boot output up until "[ 0.000000] console [tty0] enabled, bootconsole
disabled", when the rest of the boot process happened in VirtualBox.
That sounds like one would expect, no?
I don't think anyone has implemented an EFI earlyconsole yet, and you can't rely on EFI handing over the screen in a mode the kernel can handle with earlyconsole=vga, so there aren't really any other alternatives.
-hpa
Quoted 3 lines · H. Peter Anvin
I don't think anyone has implemented an EFI earlyconsole yet, and you can't rely on EFI handing over the screen in a mode the kernel can handle with earlyconsole=vga, so there aren't really any other alternatives.
Ah, ok, so what I'm looking for doesn't exist (yet?). Thanks.
~Shea
Quoted 1 line · H. Peter Anvin
I don't think anyone has implemented an EFI earlyconsole yet
I'm considering taking a shot at this. Do you have any pointers about where to look or how to approach it? Will I have to use UGA/GOP or is there some way to take advantage of the text console after exit_boot_services?
Cheers,
Shea
Quoted 3 lines
Would
keep_bootconmake any difference to your setup?
Just tried this, didn't help. Thanks though.
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Thanks,
Nish
~Shea
Quoted 7 lines · Shea Levy
Quoted 1 line · H. Peter Anvin
I don't think anyone has implemented an EFI earlyconsole yet
I'm considering taking a shot at this. Do you have any pointers about where to look or how to approach it? Will I have to use UGA/GOP or is there some way to take advantage of the text console after
exit_boot_services?
I don't think you'll need to use the graphics protocols, you should just be able to put something together using the 'output_string' function from the EFI simple text output protocol, e.g. something like this,
https://lkml.org/lkml/2012/3/16/193
Hi Matt,
Quoted 1 line · Matt Fleming
I don't think you'll need to use the graphics protocols, you should just be able to put something together using the '
output_string' function from the EFI simple text output protocol, e.g. something like this, https://lkml.org/lkml/2012/3/16/193
From the UEFI 2.3.1 spec:
Quoted 1 line
Prior to a call to
ExitBootServices(), all of the fields of the EFI System Table are valid. After an operating system has taken control of the platform with a call toExitBootServices(), only the Hdr, FirmwareVendor, FirmwareRevision, RuntimeServices, NumberOfTableEntries, and ConfigurationTable fields are valid.
Doesn't this mean that ConOut can't be used for the earlyprintk, since any bootloader (including the bootstub) will call ExitBootServices() before any printk'ing actually happens?? Or am I misunderstanding the spec somehow? I suppose I could just try it and see what happens...
Cheers,
Shea
Quoted 16 lines · Shea Levy
Hi Matt,
Quoted 4 lines · Matt Fleming
I don't think you'll need to use the graphics protocols, you should just be able to put something together using the '
output_string' function from the EFI simple text output protocol, e.g. something like this, https://lkml.org/lkml/2012/3/16/193From the UEFI 2.3.1 spec:
Quoted 5 lines
Prior to a call to
ExitBootServices(), all of the fields of the EFI System Table are valid. After an operating system has taken control of the platform with a call toExitBootServices(), only the Hdr, FirmwareVendor, FirmwareRevision, RuntimeServices, NumberOfTableEntries, and ConfigurationTable fields are valid.
Quoted 4 lines
Doesn't this mean that ConOut can't be used for the earlyprintk, since any bootloader (including the bootstub) will call
ExitBootServices()before any printk'ing actually happens?? Or am I misunderstanding the spec somehow? I suppose I could just try it and see what happens...
Oops. Good point, that isn't going to work.
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any bootloader (including the bootstub) will call
ExitBootServices()before any printk'ing actually happens?? Or am I misunderstanding the spec somehow? I suppose I could just try it and see what happens...Oops. Good point, that isn't going to work.
Surely it works fine if you are using bootstub directly from EFI ?
Quoted 5 lines · Alan Cox
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any bootloader (including the bootstub) will call
ExitBootServices()before any printk'ing actually happens?? Or am I misunderstanding the spec somehow? I suppose I could just try it and see what happens...Oops. Good point, that isn't going to work.
Surely it works fine if you are using bootstub directly from EFI ?
ConOut will work before the call to ExitBootServices(), but any bootloader (including the boot stub) calls that before starting the normal kernel boot process. I'm working on a generic earlyprintk that provides the same functionality as the existing earlyprintks that will work for any EFI boot. Matt already submitted a patch for an efi_printk that will be sufficient for the boot stub itself before the call to ExitBootServices().
~Shea
Quoted 7 lines · Alan Cox
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any bootloader (including the bootstub) will call
ExitBootServices()before any printk'ing actually happens?? Or am I misunderstanding the spec somehow? I suppose I could just try it and see what happens...Oops. Good point, that isn't going to work.
Surely it works fine if you are using bootstub directly from EFI ?
Yeah, up until the point you call ExitBootServices(), which is very early in the boot process. After that you can't rely on the validity of the console pointers in the system table.
Hey Matt,
Op 19-03-12 17:03, Matt Fleming schreef:
Quoted 10 lines · Alan Cox
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any bootloader (including the bootstub) will call
ExitBootServices()before any printk'ing actually happens?? Or am I misunderstanding the spec somehow? I suppose I could just try it and see what happens...Oops. Good point, that isn't going to work.
Surely it works fine if you are using bootstub directly from EFI ?
Yeah, up until the point you call
ExitBootServices(), which is very early in the boot process. After that you can't rely on the validity of the console pointers in the system table.
I think my system spontaneously rebooted when I tried to
do some output right after ExitBootServices when debugging the efi stub, so not only is this unreliable, it will fail to boot for at least some systems out there.
~Maarten
Quoted 9 lines · Maarten Lankhorst
Hey Matt,
Op 19-03-12 17:03, Matt Fleming schreef:
Quoted 6 lines · Alan Cox
Quoted 5 lines
Quoted 4 lines
Quoted 3 lines
any bootloader (including the bootstub) will call
ExitBootServices()before any printk'ing actually happens?? Or am I misunderstanding the spec somehow? I suppose I could just try it and see what happens...Oops. Good point, that isn't going to work.
Surely it works fine if you are using bootstub directly from EFI ?
Quoted 9 lines
Quoted 4 lines
Yeah, up until the point you call
ExitBootServices(), which is very early in the boot process. After that you can't rely on the validity of the console pointers in the system table.I think my system spontaneously rebooted when I tried to
do some output right after ExitBootServices when debugging the efi stub, so not only is this unreliable, it will fail to boot for at least some systems out there.
I would expect it to fail for just about any system.
-hpa
Signature · 2 lines
H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.