Re: scsipi: physio split the request

[mlelstv%serpens.de@localhost (Michael van Elst)]

manu%netbsd.org@localhost (Emmanuel Dreyfus) writes:

>Is there a reason other than historical for NetBSD 64kB limit?

It's a compromise. Some buffers are statically sized for MAXPHYS
and some ancient hardware cannot exceed 64k (or even less) DMA transfers.
The buffer size is mostly a problem because we don't support
scatter-gather transfers, so the buffers need to be contigous in
physical RAM (and some hardware doesn't support s-g either).

So far that's mostly a problem with software raid and modern tape I/O.

-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."