Subject: map_page() and pinned TLB entries

From: Marcelo Tosatti <[email-masked]>
Date: Thu, 16 Jun 2005 11:47:39 -0300

Hi Dan,

So we've got rid of direct pte manipulators similar to what was done in v2.4.

Such patch for v2.6 is in the 8xx tree I posted previously, you've also seen 
it here in the list. 

Remaining problem is that map_page() is going to flush the TLB for the 
addresses being created. Obviously there is a collision with the 4kb 
PTE's, which thrases the 8Mbyte entry.

So what I have done internally is to simply comment out the 
flush_HPTE() call in map_page(), which does the trick.

What would be an elegant way of dealing with this? We can insert
a conditional there such that only addresses not covered 
by other mappings (in this case the 8Mbyte entry) get flushed.

Any better ideas?

diff -Nur --exclude-from=/home/marcelo/excl /mnt/test2/tslinux_mv21/linux-2.6/arch/ppc/mm/pgtable.c linux-2.6/arch/ppc/mm/pgtable.c
--- /mnt/test2/tslinux_mv21/linux-2.6/arch/ppc/mm/pgtable.c     2005-05-16 13:19:47.000000000 -0300
+++ linux-2.6/arch/ppc/mm/pgtable.c     2005-06-16 15:52:32.000000000 -0300
@@ -299,8 +299,8 @@
        if (pg != 0) {
                err = 0;
                set_pte(pg, pfn_pte(pa >> PAGE_SHIFT, __pgprot(flags)));
-               if (mem_init_done)
-                       flush_HPTE(0, va, pmd_val(*pd));
+       //      if (mem_init_done)
+//                     flush_HPTE(0, va, pmd_val(*pd));
        }
        spin_unlock(&init_mm.page_table_lock);
        return err;