Re: Fw: Re: 2.6.17-rc1-mm1 - detects buggy TSC on GEODE
From: Jordan Crouse
Date: Sat Apr 08 2006 - 12:18:41 EST
On 07/04/06 17:41 -0700, Andrew Morton wrote:
>
> Sorry, I should have cc'ed you on this :(
No worries.
> > > 1. the new kernel is now detecting the buggy TSC on the GEODE-sc1100
> > > 2. the bug is apparently correctable by passing 'idle=poll' on kernel
> > > boot-line.
I am assuming that this is the problem where the TSC doesn't roll over
correctly on the SC1100 and SC1200.
> > John, does this mean that enable-tsc-for-amd-geode-gx-lx.patch is only safe
> > to merge after all your time-management patches have gone in?
If that is the case, then the enable-tsc-for-amd-geode-gx-lx.patch is still
safe since the TSC on the GX and LX doesn't have that same problem.
For what its worth, we used to have a fix for the TSC issue back
in the 2.4 days that looked something like this:
#ifdef CONFIG_GEODE_SC1200
#define rdtsc(low,high) \
__asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high)); \
if ((unsigned long) low > 0xFFFFFFFC) high--
#else
#define rdtsc(low,high) \
__asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high))
#endif
That seemed to work, but it is ugly, and I didn't bring it forward
when we moved to 2.6. Perhaps we can revive it if there are SC1100/SC1200
users who need it.
Thanks,
Jordan
--
Jordan Crouse
Senior Linux Engineer
AMD - Personal Connectivity Solutions Group
<www.amd.com/embeddedprocessors>
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