[parisc-linux] Re: RFC: mmap patch

[David S. Miller]

   From: Matthew Wilcox <willy@debian.org>
   Date: Sun, 9 Mar 2003 14:42:25 +0000
   
   Well.. one patch which affected us, but wouldn't affect a writethrough
   cache is:
   
   http://ftp.linux.org.uk/pub/linux/willy/patches/applied/shmem.diff
   
   In that situation, the user has no view of that page currently so they
   will read from memory.  With a writethrough cache it works without the
   flush_dcache_page(), with writeback it does not.
   
I think the real issue is SHMLBA isn't being honored, right?

The whole purpose of SHMLBA is to ensure a particular alignment
for shared memory anonymous regions, if that isn't happening anymore
that is a bug.

This is why SHMLBA is set to the virtual cache size on sparc32 for
certain cpus and on sparc64 for all cpus.