PTE entries

[Paul Mackerras]

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.