The decision is not based upon "device capable of DAC", that is
precisely my point.
The decision must be based upon a number of considerations.
1) Can it do DAC
2) Is DAC more efficient than SAC on this platform
3) Does the devices _need_ DAC even if it is slower because
it requires referencing large portions of the DMA
address space simultaneously
Sure, you could imply all of this complexity in the driver
by making them consider all of these issues when setting the
mask, but that isn't a nice interface at all.
And this still leaves the 64-bit dma_addr_t overhead issue.
David S. Miller
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to email@example.com
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/