From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 15 Jul 2003 09:25:07 -0700 From: Tom Rini To: Eugene Surovegin Cc: linuxppc-embedded@lists.linuxppc.org Subject: Re: [RFC] consistent_sync and non L1 cache line aligned buffers Message-ID: <20030715162506.GR1211@ip68-0-152-218.tc.ph.cox.net> References: <5.1.0.14.2.20030714210220.0308a070@mail.zultys.com> <5.1.0.14.2.20030714210220.0308a070@mail.zultys.com> <5.1.0.14.2.20030715091031.029e37b0@mail.ebshome.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <5.1.0.14.2.20030715091031.029e37b0@mail.ebshome.net> Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: On Tue, Jul 15, 2003 at 09:20:24AM -0700, Eugene Surovegin wrote: > At 08:46 AM 7/15/2003, Tom Rini wrote: > >Well, one thing that is worth noting is that the USB people knew this > >was a problem, and it was / should have been fixed in the 2.5 cycle. > >Similarly, SCSI was cleaned up a lot, so perhaps this has been fixed > >there. I think it's generally known that doing DMA off of the stack is > >a bad idea, and should be fixed when found. > > I agree this is VERY bad idea but the fact is that there is a code which > does such nasty things. > > I truly hope all this will/was fixed in 2.5 but frankly I wouldn't be so > sure :) Well, I would be, of the USB code. SCSI might have had it fixed, and others that we haven't found yet may or may not. But the important point is that doing this is a driver bug and it's OK to beat driver authors over the head with patches to fix the behavior. :) > Unfortunately, for production 2.5 is unusable and will be for some time. > A lot of people (I think majority) still use 2.4. And 2.4 (as of > 2.4.22-pre6) is still broken in this respect... Yes, the changes to USB and SCSI probably won't be backported for some time, if ever. So there is still a question of should we workaround this in 2.4 (Or, more to the point, do we leave it up to every $(EMBEDDED VENDOR) to do it, or bite the bullet and commit it to the 2.4 mainline. -- Tom Rini http://gate.crashing.org/~trini/ ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/