On Tue, May 18, 2004 at 08:10:19PM +0100, Peter Horton wrote: > On Tue, May 18, 2004 at 11:45:19AM -0700, Jun Sun wrote: > > > > Like others suggested, this is not the right fix. flush_page_to_ram() > > is correctly nullified. Its job should be done somewhere else > > by other routines. > > > > Here are a couple of random ideas for finding the true root cause: > > > > We know what the true root cause is :-) > > IDE PIO fills the D-cache with the read data (write allocate) as it > copies it to the page cache. > > The kernel maps the page cache page into user space ... BANG! possible > D-cache alias. > > The kernel doesn't bother flushing the page cache page from the D-cache > as it's never accessed at it's page cache address. > The kernel (or driver) should flush the page if it is mapped to user space and the content is modified. > The current fix in the Cobalt patches (2.4 & 2.6) just flushes the read > data out of the D-cache after every IDE insw()/insl(). This is the least > intrusive fix. > It should be fixed at a higher layer before we return back to userland. If you can illustrate the call stack, I can probably take a look and give my opinion. Jun
