Re: [Linux-ia64] new ia64 kernel patch (relative to 2.5.69)

David Mosberger
2003-05-12T18:40:18Z

Forgot to mention that I switched the ia64 tree from the PCI-DMA API
to the generic DMA API. Doesn't affect device drivers, but all I/O
MMU support needs to be updated accordingly. I already did swiotlb
and the HP SBA I/O MMU support. I updated that machvec definitions
for all platforms, but didn't try to update the SN-specific
implementation (since I can't test it anyhow). Updating the SN-files
should be straight-forward: you can look at swiotlb.c and
hp/common/sba_iommu.c for what needs to be done.

The one caveat is that sba_iommu.c for the moment continues to support
only PCI-devices. This shouldn't be a problem for now, but it would
be nice if someone could fix it so it can work with any device.

While working on this, I started to wonder whether or not a DMA "sync"
operation should imply a memory barrier. The API documentation is
definitely ambiguous on this point and I didn't go out to look whether
current practice is consistent (I suspect it isn't). Anyone want to
argue for or against making "sync" a memory barrier?

--david