Messages in this thread | | | Date | Thu, 28 Feb 2008 20:24:04 +0100 | From | "Klaus S. Madsen" <> | Subject | Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending |
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On Thu, Feb 28, 2008 at 09:52:57 -0800, H. Peter Anvin wrote: > Klaus S. Madsen wrote: > > > >Hope this helps. > > > > What this seems to indicate is a segfault inside VM mode that causes it > to exit to deliver the SIGSEGV, so without more information, such as > signal context, there isn't much to know about it. > > It looks like the fault happens inside the VESA BIOS, specifically VBE > function 3: > > --------V-104F03----------------------------- > INT 10 - VESA SuperVGA BIOS - GET CURRENT VIDEO MODE > AX = 4F03h > Return: AL = 4Fh if function supported > AH = status > 00h successful > BX = video mode (see #00083,#00084) > bit 13: VBE/AF v1.0P accelerated video mode > bit 14: linear frame buffer enabled (VBE v2.0+) > bit 15: don't clear video memory > 01h failed > SeeAlso: AH=0Fh,AX=4E04h,AX=4F02h > > ... which normally would be a trivial function which only reads a couple > of status words out of internal state and returns. > > **** > > Typically, when the kernel reflects an error in VM86 mode it will update > the structure in memory (in your case, the vm86plus_struct) to reflect > the context. Would it be possible for you to read it out? Hmm. As far as I can tell, its actually using the vm86old system call? That's at least what the comment in libx86 states.
However the contents of struct vm86_struct after the segfault is:
(gdb) print context.vm $2 = {regs = {ebx = 0, ecx = 0, edx = 0, esi = 0, edi = 0, ebp = 0, eax = 20227, __null_ds = 0, __null_es = 0, __null_fs = -1071579136, __null_gs = 0, orig_eax = -1, eip = 6326, cs = 49152, __csh = 0, eflags = 209410, esp = 4090, ss = 256, __ssh = 0, es = 0, __esh = 0, ds = 64, __dsh = 0, fs = 0, __fsh = 0, gs = 0, __gsh = 0}, flags = 0, screen_bitmap = 0, cpu_type = 0, int_revectored = {__map = {0, 0, 0,0, 0, 0, 0, 2147483648}}, int21_revectored = {__map = {0, 0, 0, 0, 0, 0, 0, 0}}}
My version of glibc does not seem to have vm86old declared, so I haven't tried to remove the assembly code.
Should I try to change it to use vm86, instead of vm86old?
-- Kind regards Klaus S. Madsen
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