On Sat, Jun 27, 2009 at 01:25:21PM +0200, Robert Millan wrote: > > Hi, > > Pavel pointed out earlier that sometimes when starting on i386-qemu GRUB > receives spurious events from AT keyboard. It seems that it is the role > of the firmware to flush this buffer at startup. > > Unless someone has a better idea, I would fix this with: > > - Moving at_keyboard to kernel on i386-qemu. > > - [ifdef GRUB_MACHINE_QEMU]: flush the input buffer at at_keyboard > startup by reading and discarding events for a fixed amount of time. > > I don't like that we have a race here. Suggestions welcome on how to > improve that, but TTBOMK if there's more than one event you can't tell > when you're processing the last one.
Actually I diagnosed this completely wrong. The real problem is we're using the keyboard to reboot the machine, which (at least on QEMU) results in spurious keys being put in the buffer. I think we should just jump to 0xffff0 to reboot. I didn't know back when I wrote reboot.c, but this is supposedly more reliable since we're jumping to code in ROM which hasn't been overwritten (kern/i386/pc/startup.S uses the same trick for its own grub_reboot()). See attached patch. -- Robert Millan The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and how) you may access your data; but nobody's threatening your freedom: we still allow you to remove your data and not access it at all."
2009-07-07 Robert Millan <rmh.g...@aybabtu.com> * conf/i386-coreboot.rmk (reboot_mod_SOURCES): Remove `kern/i386/reboot.c'. * kern/i386/qemu/startup.S: Include `"../realmode.S"'. (grub_reboot): New function. * kern/i386/realmode.S: Include `<grub/machine/machine.h>'. (prot_to_real): Only enable i8086 interrupts on i386-pc. * include/grub/i386/coreboot/init.h (grub_reboot): New function prototype. Index: conf/i386-coreboot.rmk =================================================================== --- conf/i386-coreboot.rmk (revision 2398) +++ conf/i386-coreboot.rmk (working copy) @@ -174,7 +174,7 @@ linux_mod_CFLAGS = $(COMMON_CFLAGS) linux_mod_LDFLAGS = $(COMMON_LDFLAGS) # For reboot.mod. -reboot_mod_SOURCES = commands/reboot.c kern/i386/reboot.c +reboot_mod_SOURCES = commands/reboot.c reboot_mod_CFLAGS = $(COMMON_CFLAGS) reboot_mod_LDFLAGS = $(COMMON_LDFLAGS) Index: kern/i386/qemu/startup.S =================================================================== --- kern/i386/qemu/startup.S (revision 2398) +++ kern/i386/qemu/startup.S (working copy) @@ -95,3 +95,11 @@ codestart: /* This should never happen. */ jmp EXT_C(grub_stop) + +#include "../realmode.S" + +FUNCTION(grub_reboot) + call prot_to_real + .code16 + ljmp $0xf000, $0xfff0 + .code32 Index: kern/i386/realmode.S =================================================================== --- kern/i386/realmode.S (revision 2398) +++ kern/i386/realmode.S (working copy) @@ -41,6 +41,8 @@ * with "ret $N" where N is ((the number of arguments) - 3) * 4. */ +#include <grub/machine/machine.h> + /* * This is the area for all of the special variables. */ @@ -215,8 +217,10 @@ realcseg: movw %ax, %gs movw %ax, %ss +#ifdef GRUB_MACHINE_PCBIOS /* restore interrupts */ sti +#endif /* return on new stack! */ DATA32 ret Index: include/grub/i386/coreboot/init.h =================================================================== --- include/grub/i386/coreboot/init.h (revision 2398) +++ include/grub/i386/coreboot/init.h (working copy) @@ -1,6 +1,6 @@ /* * GRUB -- GRand Unified Bootloader - * Copyright (C) 2007 Free Software Foundation, Inc. + * Copyright (C) 2007,2009 Free Software Foundation, Inc. * * GRUB is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -24,5 +24,6 @@ void EXPORT_FUNC(grub_stop) (void) __attribute__ ((noreturn)); void EXPORT_FUNC(grub_stop_floppy) (void); +void EXPORT_FUNC (grub_reboot) (void) __attribute__ ((noreturn)); #endif
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