Re: i686 quirk for AMD Geode

Andres Salomon
2009-11-08T16:10:04Z

See comment below. BTW, how does this affect performance on LXs?
Do you have any hard numbers for common tasks?

On Sat, 7 Nov 2009 12:11:55 +0100
Matteo Croce <technoboy85@gmail.com> wrote:
[...]
>
> --- a/arch/x86/kernel/Makefile 2009-11-06 15:06:52.246223989
> +0100 +++ b/arch/x86/kernel/Makefile 2009-11-06
> 15:07:04.294054613 +0100 @@ -89,7 +89,7 @@
> obj-$(CONFIG_HPET_TIMER) += hpet.o
>
> obj-$(CONFIG_K8_NB) += k8.o
> -obj-$(CONFIG_MGEODE_LX) += geode_32.o mfgpt_32.o
> +obj-$(CONFIG_MGEODE_LX) += geode_32.o mfgpt_32.o
> nopl_emu.o obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o
> obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o
>
> --- a/arch/x86/kernel/cpu/amd.c 2009-11-06 15:06:52.254223805
> +0100 +++ b/arch/x86/kernel/cpu/amd.c 2009-11-06
> 15:07:04.294054613 +0100 @@ -138,8 +138,10 @@
> }
>
> if (c->x86_model == 10) {
> - /* AMD Geode LX is model 10 */
> - /* placeholder for any needed mods */
> + /* Geode only lacks the NOPL instruction to be i686,
> + but we can emulate it in the exception handler
> + and promote it to a class 6 cpu */
> + boot_cpu_data.x86 = 6;
> return;
> }

If you're going to update this, you also need to make sure that you're
not breaking things that check it. For example,
arch/x86/include/asm/geode.h has an is_geode_lx check that expects
boot_cpu_data.x86 to be 5. Please be sure to update all these places
when creating a patch like this.