Re: [Linux-3D] Try my new DMA kernel functions
Richard Gooch (Richard.Gooch@atnf.CSIRO.AU)
Wed, 10 Jun 1998 09:30:20 +1000
Alan Cox writes:
> > > I care about - firstly mmap /dev/mem, start video grabbing on it, secondly
> > > grabbing into the image part of a sys5 shared memory MITSHM block.
> >
> > sys5 shared memory is stupid and obsolete. It's good to have the
> > facility around so that stupid and obsolete programs still work, but
> > when considering radical new OS features, we shouldn't design them
> > around ancient quirks that no wise programmer will use in new code.
>
> Stupid, obsolete humm - video folks do DMA to MITSHM X objects because its
> FAST, way faster than the alternatives generally available. I doubt they
> generally give a hoot about SYS5 v BSD shm arguments at all.
SysV SHM still has advantages over mmap. I'd find mmap much more
useful if I could mmap /dev/zero, pass the FD to another process and
mmap there and hence share memory between the two.
Regards,
Richard....
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