On Sun, 28 Sep 2008 20:49:26 +0200 Joerg Roedel <[EMAIL PROTECTED]> wrote:
> On Sun, Sep 28, 2008 at 11:21:26PM +0900, FUJITA Tomonori wrote: > > On Mon, 22 Sep 2008 20:21:12 +0200 > > Joerg Roedel <[EMAIL PROTECTED]> wrote: > > > > > Hi, > > > > > > this patch series implements stackable dma_ops on x86. This is useful to > > > be able to fall back to a different dma_ops implementation if one can > > > not handle a particular device (as necessary for example with > > > paravirtualized device passthrough or if a hardware IOMMU only handles a > > > subset of available devices). > > > > We already handle the latter. This patchset is more flexible but > > seems to incur more overheads. > > > > This feature will be used for only paravirtualized device passthrough? > > If so, I feel that there is more simpler (and specific) solutions for > > it. > > Its not only for device passthrough. It handles also the cases where a > hardware IOMMU does not handle all devices in the system (like in some > Calgary systems but also possible with AMD IOMMU). With this patchset we I know that. As I wrote in the previous mail, we already solved that problem with per-device-dma-ops. My question is what unsolved problems this patchset can fix? This patchset is named "stackable dma_ops" but it's different from what we discussed as "stackable dma_ops". This patchset provides IOMMUs a generic mechanism to set up "stackable dma_ops". But this patchset doesn't solve the problem that a hardware IOMMU does not handle all devices (it was already solved with per-device-dma-ops). If paravirtualized device passthrough still needs to call multiple dma_ops, then this patchset doesn't solve that issue. > can handle these cases in a generic way without hacking it into the > hardware drivers (these hacks are also in the AMD IOMMU code and I plan > to remove them in the case this patchset will be accepted). -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html