Messages in this thread | | | Subject | RE: Updated MSI Patches | Date | Tue, 12 Aug 2003 10:32:39 -0700 | From | "Nguyen, Tom L" <> |
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> > There are two types of MSI capable devices: one supports the MSI > > capability structure and other supports the MSI-X capability structure. > > The patches provide two APIs msix_alloc_vectors/msix_free_vectors for > > only devices, which support the MSI-X capability structure, to request > > for additional messages. By default, each MSI/MSI-X capable device > > function is allocated with one vector for below reasons: > > - To achieve a backward compatibility with existing drivers if possible. > > - Due to the current implementation of vector assignment, all devices > > that support the MSI-capability structure work with no more than one > > allocated vector. > > - The hardware devices, which support the MSI-X capability structure, > > may indicate the maximum capable number of vectors supported (32 > > vectors as example). However, the device drivers may require only > > four. With provided APIs, the optimization of MSI vector allocation > > is achievable.
> IMO Multiplexing would be preferred, we can't be allocating that many > vectors for one device/device driver All pre-assigned vectors to all enabled IOxAPIC(s) are reserved. Allocating additional vectors to MSI-X driver is determined based on the available vectors, which must be greater than the number of vectors requested by MSI-X driver.
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