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Re: [PATCH] hp-timing for ppc32/64
- From: Benjamin Herrenschmidt <benh at kernel dot crashing dot org>
- To: Steve Munroe <sjmunroe at us dot ibm dot com>
- Cc: libc-alpha at sources dot redhat dot com, Tom Gall <tom_gall at vnet dot ibm dot com>
- Date: Tue, 15 Nov 2005 08:32:16 +1100
- Subject: Re: [PATCH] hp-timing for ppc32/64
- References: <OF4F9CAE0F.AA0E29B9-ON862570B9.0072D33E-862570B9.00750C76@us.ibm.com>
> On x86 they only implement hp-timing on i686 and newer based on the "Time
> Stamp Counter" and the "read time-stamp counter" instruction. Since they
> only have one "kind" of timebase they don't need to access dl_hwcap in
> hp-timing. This is also true for alpha, ia64, sparc, X86_64 and powerpc64.
> It would be true for ppc32 except for the 601 and 403 chips ...
How do they know that they are running on i686 ?
> The whole idea of hp-timing is that is fast, simple, and inline code. It
> is not a general purpose clock. It must also work in the restricted
> environment of the dynamic loader itself, like before and the durring the
> time the loader is relocating its self!
AT_HWCAP is available at all time since it's passed by the kernel
Ben.