Re: [Fastboot] [RFC] ELF Relocatable x86 and x86_64 bzImages

H. Peter Anvin
2006-08-03T04:54:21Z

Eric W. Biederman wrote:
> Don Zickus <dzickus@redhat.com> writes:
>
>>> There is one outstanding issue where I am probably requiring too much
>> alignment
>>> on the arch/i386 kernel.
>> There was posts awhile ago about optimizing the kernel performance by
>> loading it at a 4MB offset.
>>
>> http://www.lkml.org/lkml/2006/2/23/189
>>
>> Your changes breaks that on i386 (not aligned on a 4MB boundary). But a
>> 5MB offset works. Is that the correct update or does that break the
>> original idea?
>
> That patch should still apply and work as described.
>
> Actually when this stuipd cold I have stops slowing me down,
> and I fix the alignment to what it really needs to be ~= 8KB.
>
> Then bootloaders should be able to make the decision.
>
> HPA Does that sound at all interesting?
>

I'm sorry, it's not clear to me what you're asking here.

The bootloaders will load bzImage at the 1 MB point, and it's up to the
decompressor to locate it appropriately. It has (correctly) been
pointed out that it would be faster if the decompressed kernel is
located to the 4 MB point -- large pages don't work below 2/4 MB due to
interference with the fixed MTRRs -- but that's doesn't affect the boot
protocol in any way.

I was under the impression that your relocatable patches allows the boot
loader to load the bzImage at a different address than the usual
0x100000; but again, that shouldn't affect the kernel's final resting place.

-hpa