> -----Original Message----- > From: Bjorn Helgaas [mailto:[email protected]] > Sent: Friday, January 15, 2016 7:23 PM > To: David Woodhouse <[email protected]> > Cc: Lawrynowicz, Jacek <[email protected]>; > [email protected]; Joerg Roedel <[email protected]> > Subject: Re: [PATCH] iommu/vt-d: Add support for multiple DMA aliases > > On Wed, Jan 13, 2016 at 1:28 PM, David Woodhouse > <[email protected]> wrote: > > On Mon, 2016-01-11 at 14:20 +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%2 > >> 0MulitHostSystemDesigns.pdf > >> > >> Signed-off-by: Jacek Lawrynowicz <[email protected]> > > > > Acked-by: David Woodhouse <[email protected]> > > > > Strictly speaking, this is more in PCI code than IOMMU code. And it > > doesn't actually touch the Intel VT-d code at all; the subject is a > > bit misleading. > > > > But I'm happy enough to add it to my intel-iommu tree if nobody else > > picks it up. Bjorn? > > Jacek, would you mind posting this to [email protected], please?
Sure, no problem. -- Jacek Lawrynowicz Intel Technology Poland sp. z o.o. KRS 101882 - ul. Slowackiego 173, 80-298 Gdansk _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
