Re: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpuarea

[H. Peter Anvin]

Jeremy Fitzhardinge wrote:
> Yes, and there's no reason we couldn't do the same on 64-bit, aside from 
> the stack-protector's use of %gs:40.  There's no code-size cost in large 
> offsets, since they're always 32-bits anyway (there's no short absolute 
> addressing mode).
>
> If we manually generate %gs-relative references to percpu data, then 
> it's no different to what we do with 32-bit, whether it be a specific 
> symbol address or using the TLS relocations.

If we think the problem is the zero-basing triggering linker bugs, we 
should probably just use a small offset, like 64 (put a small dummy 
section before the .percpu.data section to occupy this section.)

I'm going to play with this a bit and see if I come up with something 
sanish.

	-hpa
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