Messages in this thread | | | Date | Wed, 19 Nov 2008 10:36:11 +0100 | From | Ingo Molnar <> | Subject | Re: [GIT PULL] AMD IOMMU updates for 2.6.28-rc5 |
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* Joerg Roedel <joro@8bytes.org> wrote:
> We can't test all drivers for those bugs until 2.6.28 will be > released. And these bugs can corrupt data, for example when a driver > frees dma addresses allocated by another driver and these addresses > are then reallocated. > > The only way to protect the drivers from each other is to isolate > them in different protection domains. The AMD IOMMU driver prints a > WARN_ON() if a driver frees dma addresses not yet mapped. This > triggered with the bnx2 and the ixgbe driver. > > And the data corruption is real, it eat the root-fs of my testbox > one time.
a WARN_ON() can be acted upon much easier than silent/spurious data corruption. So printing a WARN_ON() will result in drivers being fixed a lot faster (and with a lot less debugging needed) than if we were intentionally letting DMA corruption happen. The WARN_ON() will be routed to kerneloops.org on the major distros, etc. etc.
> I agree that we need to fix the drivers. I plan to implement some > debug code which allows driver developers to detect those bugs even > if they have no IOMMU in the system.
That would be _really_ nice to have.
Ingo
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