> -----Original Message----- > From: David Woodhouse [mailto:[email protected]] > Sent: Friday, January 8, 2016 3:40 PM > To: Lawrynowicz, Jacek <[email protected]>; > [email protected] > Subject: Re: [PATCH] iommu/vt-d: Add support for multiple DMA aliases > > On Fri, 2015-11-06 at 16:21 +0100, Jacek Lawrynowicz wrote: > > This patch solves IOMMU support issues with PCIe non-transparent bridges > > that use Requester ID look-up tables (LUT), e.g. PEX8733. Before exiting > > the bridge, packet's RID is rewritten according to LUT programmed by > > a driver. Modified packets are then passed to a destination bus and > > processed upstream. The problem is that such packets seem to come from > > non-existent nodes that are hidden behind NTB and are not discoverable > > by a destination node, so IOMMU discards them. Adding DMA alias for a > > given LUT entry allows IOMMU to create a proper mapping that enables > > inter-node communication. > > > > The current DMA alias implementation supports only single alias, so it's > > not possible to connect more than two nodes when IOMMU is enabled. > This > > implementation enables all possible aliases on a given bus (256) that > > are stored in a bitset. Alias devfn is directly translated to a bit > > number. The bitset is not allocated for devices that have no need for > > DMA aliases. > > > > More details can be found in following article: > > > http://www.plxtech.com/files/pdf/technical/expresslane/RTC_Enabling%20 > MulitHostSystemDesigns.pdf > > > > Signed-off-by: Jacek Lawrynowicz <[email protected]> > > Acked-by: David Woodhouse <[email protected]> > > Seems reasonable to me. Jörg?
Original patch got a bit old so I rebased it on Jörg's tree and submitted once again. -- Jacek Lawrynowicz Intel Technology Poland sp. z o.o. KRS 101882 - ul. Slowackiego 173, 80-298 Gdansk
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