From: Andrei Borzenkov <arvidjaar@gmail.com>
To: The development of GNU GRUB <grub-devel@gnu.org>,
Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
Subject: Re: "Illegal Instruction" error in grub_script_comments
Date: Thu, 20 Oct 2016 20:34:51 +0300 [thread overview]
Message-ID: <a58beafb-4650-5ab2-a7f8-84a0a972dbda@gmail.com> (raw)
In-Reply-To: <909472052.9545840.1476891128586.JavaMail.zimbra@redhat.com>
19.10.2016 18:32, Matthew Whitehead пишет:
> 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?
>
This code is likely grub_cpu_is_tsc_supported() (see
include/grub/i386/tsc.h) which *is* protected by
grub_cpu_is_cpuid_supported(). Can you test if this function yields
wrong result in your case (just compile it separately)?
> - Matthew
>
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
>
prev parent reply other threads:[~2016-10-20 17:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-17 18:34 "Illegal Instruction" error in grub_script_comments tedheadster
2016-10-17 22:32 ` Colin Watson
2016-10-18 19:12 ` Lennart Sorensen
2016-10-19 15:32 ` Matthew Whitehead
2016-10-19 19:06 ` Lennart Sorensen
2016-10-19 19:16 ` Matthew Whitehead
2016-10-31 3:17 ` Matthew Whitehead
2016-10-20 17:34 ` Andrei Borzenkov [this message]
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