> > +What: /sys/kernel/iommu_groups/<grp_id>/type
> > +Date: February 2020 > > +KernelVersion: v5.6 > > +Contact: Sai Praneeth Prakhya > > <sai.praneeth.prak...@intel.com<mailto:sai.praneeth.prak...@intel.com>> > > +Description: Lets the user know the type of default domain in > > use by iommu > > + for this group. A privileged user could request > > kernel to change > > Let the users know the default domain type of the IOMMU group by reading this > file. A privileged user could request to change it by writing to this file. Sure! Will fix it. > > + the group type by writing to this file. Presently, > > only three > > + types are supported > > + 1. DMA: All the DMA transactions from the devices in > > this group > > + are translated by the iommu. > > + 2. identity: All the DMA transactions from the > > devices in this > > + group are *not* translated by the > > iommu. > > + 3. auto: Kernel decides one among DMA/identity mode > > and > hence > > + when the user reads the file he would > > never see "auto". > > Just out of curiosity, when could a user reads "auto" from this file? Never, because when a user requests kernel to change to "auto" mode, kernel will select one among identity or DMA. So, default domain type cannot be auto, it's always either identity or DMA. "auto" mode is just a write value where user is requesting kernel to select one among identity or DMA. > > + This is just a write only value. > > + Note: > > + ----- > > + A group type could be modified only when *all* the > > devices in > > group's default domain type (not group type). Sure! Makes sense.. will fix it 😊 > > > + the group are not binded to any device driver. So, > > the user has > > bound Makes sense.. will fix this too. Regards, Sai
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