On Wed, Oct 18, 2006 at 02:37:23PM -0700, Andrew Morton wrote: > > argh, you removed the mailing list from cc. Sorry, I'm still lacking proper etiquette. > > On Wed, 18 Oct 2006 11:54:53 -0500 > "Mike Miller (OS Dev)" <mikem@xxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > On Tue, Oct 17, 2006 at 05:10:21PM -0700, Andrew Morton wrote: > > > On Tue, 17 Oct 2006 16:13:03 -0500 > > > "Mike Miller (OS Dev)" <mikem@xxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > PATCH 2/2 > > > > Turned off DMA prefetch for the P600 on systems which may present > > > > discontiguous memory. > > > > > > > > > > What do you mean by "discontiguous memory"? CONFIG_DISCONTIGMEM? > > > > The IPF memory map can have holes between the different regions. I've > > been told by our HW guys that AMD may also have holes. > > Pretty much all platforms/architectures have holes in their physical memory > map. > > > > > > > > What is the actual problem which is being fixed here? > > > > Sorry, I should have been clearer. There is a bug in the DMA engine that > > that may result in prefetching data from beyond the end of memory or > > falling off into one the holes on IPF and AMD. It causes a machine check > > when that happens. > > It doesn't happen on Proliant because the last 4kB (or so) of memory is > > mapped out by the BIOS and Pentium guarantees contiguous memory. > > I think that this: > > > > #if defined(CONFIG_IA64) || defined(CONFIG_X86_64) > > is nowhere near strong enough and is probably inappropriate. > > It _could_ be that CONFIG_DISCONTIGMEM|CONFIG_SPARSEMEM will be closer, but > even CONFIG_FLATMEM systems can have holes. I'm poking around on some IPF platforms. It looks like CONFIG_DISCONTIGMEM is set on them, but not the others you mention. Would that be sufficient? > > On what machines can/does this card exist? Things like powerpc? This problem was found on Itanium. We don't try to support powerpc. Thanks, mikem - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
