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

From: H. Peter Anvin
Date: Thu Aug 03 2006 - 00:52:05 EST

Eric W. Biederman wrote:
Don Zickus <dzickus@xxxxxxxxxx> writes:

There is one outstanding issue where I am probably requiring too much
on the arch/i386 kernel.
There was posts awhile ago about optimizing the kernel performance by
loading it at a 4MB offset.

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.


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