search for: ddw

...new virtio devices, otherwise, it should be specified per device as an attribute of the device instance. I would argue that we should default to "bypass IOMMU" on *all* architecture due to the performance impact, and to essentially default to the same behaviour as today. With things like DDW even powerpc might be able to mostly alleviate the performance impact so we might to change in the long term, but I tend to prefer more incremental approaches. > New QEMU > always advertises this feature flag. If iommu=on, QEMU's virtio > devices refuse to work unless the driver ac...

...new virtio devices, otherwise, it should be specified per device as an attribute of the device instance. I would argue that we should default to "bypass IOMMU" on *all* architecture due to the performance impact, and to essentially default to the same behaviour as today. With things like DDW even powerpc might be able to mostly alleviate the performance impact so we might to change in the long term, but I tend to prefer more incremental approaches. > New QEMU > always advertises this feature flag. If iommu=on, QEMU's virtio > devices refuse to work unless the driver ac...

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...ommu. I *think* that x86 supports that. IOW x86 would always set the feature flag. > > I would argue that we should default to "bypass IOMMU" on *all* > architecture due to the performance impact, and to essentially > default to the same behaviour as today. With things like DDW even > powerpc might be able to mostly alleviate the performance impact > so we might to change in the long term, but I tend to prefer > more incremental approaches. As above, there's a difference between "bypass IOMMU" and "there is no IOMMU". x86 and, I think, m...

On 29/07/2015 02:47, Andy Lutomirski wrote: > > > If new kernels ignore the IOMMU for devices that don't set the flag > > > and there are physical devices that already exist and don't set the > > > flag, then those devices won't work reliably on most modern > > > non-virtual platforms, PPC included. > > > > Are there many virtio physical

On 29/07/2015 02:47, Andy Lutomirski wrote: > > > If new kernels ignore the IOMMU for devices that don't set the flag > > > and there are physical devices that already exist and don't set the > > > flag, then those devices won't work reliably on most modern > > > non-virtual platforms, PPC included. > > > > Are there many virtio physical

...t x86 supports that. IOW x86 would > always set the feature flag. Ok. > > I would argue that we should default to "bypass IOMMU" on *all* > > architecture due to the performance impact, and to essentially > > default to the same behaviour as today. With things like DDW even > > powerpc might be able to mostly alleviate the performance impact > > so we might to change in the long term, but I tend to prefer > > more incremental approaches. > > As above, there's a difference between "bypass IOMMU" and "there is no > IOM...

...t x86 supports that. IOW x86 would > always set the feature flag. Ok. > > I would argue that we should default to "bypass IOMMU" on *all* > > architecture due to the performance impact, and to essentially > > default to the same behaviour as today. With things like DDW even > > powerpc might be able to mostly alleviate the performance impact > > so we might to change in the long term, but I tend to prefer > > more incremental approaches. > > As above, there's a difference between "bypass IOMMU" and "there is no > IOM...

...would >> always set the feature flag. > > Ok. > >> > I would argue that we should default to "bypass IOMMU" on *all* >> > architecture due to the performance impact, and to essentially >> > default to the same behaviour as today. With things like DDW even >> > powerpc might be able to mostly alleviate the performance impact >> > so we might to change in the long term, but I tend to prefer >> > more incremental approaches. >> >> As above, there's a difference between "bypass IOMMU" and "t...

On Tue, Jul 28, 2015 at 12:33 PM, Jan Kiszka <jan.kiszka at siemens.com> wrote: > On 2015-07-28 21:24, Andy Lutomirski wrote: >> On Tue, Jul 28, 2015 at 12:06 PM, Jan Kiszka <jan.kiszka at siemens.com> wrote: >>> On 2015-07-28 20:22, Andy Lutomirski wrote: >>>> On Tue, Jul 28, 2015 at 10:17 AM, Jan Kiszka <jan.kiszka at siemens.com> wrote:

On Tue, Jul 28, 2015 at 12:33 PM, Jan Kiszka <jan.kiszka at siemens.com> wrote: > On 2015-07-28 21:24, Andy Lutomirski wrote: >> On Tue, Jul 28, 2015 at 12:06 PM, Jan Kiszka <jan.kiszka at siemens.com> wrote: >>> On 2015-07-28 20:22, Andy Lutomirski wrote: >>>> On Tue, Jul 28, 2015 at 10:17 AM, Jan Kiszka <jan.kiszka at siemens.com> wrote:

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