[coreboot] [PATCH] faster AP launch for recent AMD processors
Myles Watson
mylesgw at gmail.com
Mon Oct 18 19:04:46 CEST 2010
> To reduce boot time, removing the double startup IPI and 10 ms
> delay from lapic_cpu_init.c should be considered. Because I can
> test this code only on recent AMD cpu models, it is only safe
> to apply the change in those cases. The following patch uses
> a compile time check to identify CPUs where the change is known
> to work. Would a runtime check be better?
Until Fam10 and K8 can use the same image, compile time is probably the
correct way to do it. If there ends up being a long list of processors that
don't need the wait, we could add a Kconfig option like
CONFIG_NO_LAPIC_DELAY.
> Signed-off-by: Scott Duplichan <scott at notabs.org>
Acked-by: Myles Watson <mylesgw at gmail.com>
> + #if !defined (CONFIG_CPU_AMD_MODEL_10XXX) && !defined
> (CONFIG_CPU_AMD_MODEL_14XXX)
> mdelay(10);
> + #endif
>
> printk(BIOS_SPEW, "Deasserting INIT.\n");
>
> @@ -144,6 +146,9 @@
> #endif
>
> num_starts = 2;
> + #if defined (CONFIG_CPU_AMD_MODEL_10XXX) || defined
> (CONFIG_CPU_AMD_MODEL_14XXX)
> + num_starts = 1;
> + #endif
I'd prefer it if they both used the same logic. I think it will make it
easier to update in the future. Maybe something like this:
#if !defined (CONFIG_CPU_AMD_MODEL_10XXX) && !defined
(CONFIG_CPU_AMD_MODEL_14XXX)
num_starts = 2;
#else
num_starts = 1;
#endif
Thanks,
Myles
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