Messages in this thread | | | Subject | Re: [Fdutils] DMA cache consistency bug introduced in 2.6.28 | From | "Pallipadi, Venkatesh" <> | Date | Thu, 14 Jan 2010 18:01:57 -0800 |
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On Tue, 2010-01-12 at 01:04 -0800, Mark Hounschell wrote: > On 01/11/2010 07:19 PM, Pallipadi, Venkatesh wrote: > > > > Sorry for not following up on this. We have narrowed this down to HPET > > MSI and floppy DMA. I still don't know how HPET MSI interrupts are > > breaking floppy DMA. > > > > You are seeing the problem on two different systems. Correct? Do you > > have any system where this works with HPET MSI enabled? > > > > I see the problem on every system in which the HPET2 shows up in > /proc/interrupts. The machines that work with HPET enabled don't show HPET > at all in /proc/interrupts. I have some of each. All the boxes that fail > here use the (AMD) 790x series chip sets. > > > Couple of options on how we can go about this one: > > 1) Change the HPET-MSI change to not get activated when there are no > > C-states with LAPIC stoppage involved. This will resolve the problem on > > the systems you reported as there are no deep C-states. But, I fear that > > with the actual problem unresolved, we may hit it in future with this or > > some other platform having same issue with CPUs that support deep > > C-state. > > 2) Try this testcase on few other platforms that support HPET-MSI and > > deep C-states and check how widespread the problem is and then add a > > whitelist-blacklist for HPET MSI usage. > > > > I think, for 2.6.33 option 1 is better. Will work on that and send in > > patches for you test. > > >
Mark,
I just sent out a patchset that should workaround the problem here. Can you check and let me know whether thats the case.
We will still need a simpler/smaller workaround for .33. Will send a patch for that soon.
Also, are you testing this with usb floppy controller? I tried to test it on my end, but fdformat doesn't seem to like my usb floppy drive. I tried, 'ufiformat -f 1440 <dev>', with which I am not able to reproduce the failure on any of my boxes. Not sure whether that really means I don't hit this bug or that is going through totally different code path.
Thanks, Venki
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