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Date: Thu, 3 May 2007 08:03:25 +1000
From: Paul Mackerras <paulus@samba.org>
To: "Siva Prasad" <sprasad@bivio.net>
Subject: RE: PTE entries
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Siva Prasad writes:

> Are there any other places where we have self modifying code in Linux
> kernel, other than in arch/powerpc/mm/ppc_mmu_32.c:MMU_init_hw()
> (basically modified create_hpte and flush_hash_page)

Yes, the cpu feature stuff writes nops over various bits of code
depending on what cpu you're running on.  See do_feature_fixups() in
arch/powerpc/kernel/cputable.c.

> Instead of using addis, why can't we move it from SDR1 register and mask
> the second half. SDR1 has the required value. Right?
> May be I am missing something here.

mtspr is slow on most processors, certainly slower than addis.

Paul.