Re: [RFC PATCH 1/3] Replace paravirt_probe with "platform type" bootheader field

From: H. Peter Anvin
Date: Fri May 04 2007 - 13:14:31 EST


Eric W. Biederman wrote:
> "H. Peter Anvin" <hpa@xxxxxxxxx> writes:
>
>> Eric W. Biederman wrote:
>>> Unlikely. Unless we expect that this offset will come in non-zero.
>>>
>> You might have to worry about that. Historically, the "zero-page" was
>> really just the setup code overwritten, and it's still true for a big
>> chunk of it.
>>
>> One of the major changes in my setup code rewrite is to start out with
>> an all-zero chunk of memory for this.
>
> Well as long as we are in sync with setup.S we are fine. The issue
> is people generating the real-mode data from scratch, when using the
> 32bit entry point.

Point. I'd like that interface to specify that any undefined fields
should be zero, or we have a hopeless situation on our hands.

By the way, see the following for the structure definition; prepare to barf:

http://git.kernel.org/?p=linux/kernel/git/hpa/linux-2.6-newsetup.git;a=blob;f=arch/i386/boot/boot.h;h=41a16f96ac3476cbd969aabe5e6a792ffe8c64a0;hb=HEAD

[I intend to move this into include/asm-i386/boot.h, but haven't gotten
that far yet. I just yesterday got the code booting on both i386 and
x86-64, but haven't committed all the include/asm-* mods that went a
long with that yet. I'm also waiting for a Kbuild fix so that the boot
directory can be shared between i386 and x86-64 without requiring a
symlink in the source tarball.]

-hpa
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