Re: "Illegal Instruction" error in grub_script_comments

[Matthew Whitehead]

Lennart,
  I think I found the problem. I don't know what kernel.img does, but I'm 
guessing it is an essential part of grub2, loading after the 1st and 2nd stage 
loaders? I disassembled the binary using 'objdump -D -b binary -m i386 
kernel.img' and found several cases both of rdtsc and cpuid. Both of these 
instructions do not exist on first generation 80486 cpus. Here they are, and 
I've attached the full disassembly output.

    53a0:       85 c0                   test   %eax,%eax
    53a2:       74 6f                   je     0x5413
    53a4:       b8 01 00 00 00          mov    $0x1,%eax
    53a9:       0f a2                   cpuid
    53ab:       80 e2 10                and    $0x10,%dl
    53ae:       74 63                   je     0x5413
    53b0:       31 c0                   xor    %eax,%eax
    53b2:       0f a2                   cpuid
    53b4:       0f 31                   rdtsc
    53b6:       a3 48 67 01 00          mov    %eax,0x16748
    53bb:       89 15 4c 67 01 00       mov    %edx,0x1674c
    53c1:       31 c0                   xor    %eax,%eax
    53c3:       0f a2                   cpuid
    53c5:       0f 31                   rdtsc
    53c7:       89 c6                   mov    %eax,%esi
    53c9:       b8 ff ff 00 00          mov    $0xffff,%eax
    53ce:       89 d7                   mov    %edx,%edi
    53d0:       e8 83 00 00 00          call   0x5458
    53d5:       31 c0                   xor    %eax,%eax
    53d7:       0f a2                   cpuid
    53d9:       0f 31                   rdtsc
    53db:       89 45 e0                mov    %eax,-0x20(%ebp)
    53de:       8b 4d e0                mov    -0x20(%ebp),%ecx
...
    5439:       31 c0                   xor    %eax,%eax
    543b:       0f a2                   cpuid
    543d:       0f 31                   rdtsc
    543f:       8b 0d 50 67 01 00       mov    0x16750,%ecx
    5445:       6a 00                   push   $0x0
    5447:       e8 8f dc ff ff          call   0x30db

How can we adjust the makefiles to include -march=i486 or something similar?

- Matthew

kernel.dis
Description: application/vnd.mobius.dis