Re: [PATCH v3 01/12] x86, boot: move verify_cpu.S after 0x200

From: Eric W. Biederman
Date: Thu Nov 22 2012 - 18:34:28 EST


Yinghai Lu <yinghai@xxxxxxxxxx> writes:

> On Wed, Nov 21, 2012 at 11:50 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>> The comment is just plain wrong. It assumes you're loading an ELF file,
>> whereas in practice that is rarely true.
>>
>> This does explain why the poor ABI, though. A jump table at the
>> beginning would have been a lot cleaner.
>
> Can you please have patch to update the comments and point to the API there ?

Long ago and far away. I wrote the 64bit entry code for a bzImage by
putting an ELF header in the boot sector. That is what that comment
referred to when it was written. Andrew had a problem on one of his
test machines and so the patch to bootsector was dropped.

Booting with a vmlinux file does (or at least should not) need this.
ELF loaders will pick the entry point out from the ELF header.

I don't know what has happened in the intervening time, or who if anyone
has depended on that offset. The original intent an internal use hard
code.

Eric



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