Re: [x86, vdso] BUG: unable to handle kernel paging request at d34bd000

[Linus Torvalds]

On Mon, Mar 10, 2014 at 1:19 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> If the only immediate problem is the code generation size, then Andy
> already had a (simpler) hack-around:
>
>   #undef CONFIG_OPTIMIZE_INLINING
>   #undef CONFIG_X86_PPRO_FENCE
>
> in vclock_gettime.c

Btw, we should seriously consider getting rid of CONFIG_X86_PPRO_FENCE.

It was of questionable value to begin with, and I think that the
actual PPro bug is about one of

 - Errata 66, "Delayed line invalidation".
 - Errata 92, "Potential loss of data coherency"

both of which affect all PPro versions afaik (there is also a UP
errata 51 wrt ordering of cached and uncached accesses that was fixed
in the sB1 stepping).

And as far as I know, we have never actually seen the bug in real
life, EVEN WHEN PPRO WAS COMMON. The workaround was always based on
knowledge of the errata afaik.

So I do think we might want to consider retiring that config option
entirely as a "historical oddity".

And very much so for the vdso case. Do we even do the asm alternative
fixups for the vdso?

I also suspect we should get rid of CONFIG_X86_OOSTORE, or at least
limit it to !SMP - I don't think anybody ever made SMP systems with
those IDT/Centaur Winchip chips in them.

                Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/