Re: [Fwd: [parisc-linux] Problems with raw interface.]

[Matthew Wilcox <willy@debian.org>]

On Sat, Sep 20, 2003 at 11:35:55PM -0600, Grant Grundler wrote:
> BTW, kernel and user space will alias to different cachelines
> for the same 32-bit "offset" because of "Space Registers"
> (form of segmented addressing).

Rubbish, they alias to the same cachelines because of the 4MB get-out
clause.  What you may have meant is that the same page accessed through
user and kernel mappings will alias to different cachelines because
their addresses *aren't* congruent modulo 4MB.

> > The key places are rw_raw_dev(), where we set up the virtual address to
> > physical page mappings, and brw_kiovec(), where the actual physical page
> > IO is done.
> 
> I can look, but willy or jejb have much better chance of finding
> something...

Those functions don't seem to exist in 2.6.  The only reference is:
./Documentation/block/biodoc.txt: of data, so brw_kiovec() invokes ll_rw_kio for each kiobuf in a kiovec.
which seems to be an orphaned comment.

I'll reluctantly take a look at 2.4.

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk