cvs commit: src/sys/alpha/alpha busdma_machdep.c

[John Baldwin]

On Thursday 15 September 2005 03:15 pm, Scott Long wrote:
> John Baldwin wrote:
> > On Thursday 15 September 2005 01:09 pm, John Baldwin wrote:
> >>jhb         2005-09-15 17:09:42 UTC
> >>
> >>  FreeBSD src repository
> >>
> >>  Modified files:
> >>    sys/alpha/alpha      busdma_machdep.c
> >>  Log:
> >>  Add a memory barrier for PREWRITE operations to ensure all writes by
> >> the CPU have drained before further writes to kick off the operation.
> >
> > Other architectures with relaxed memory ordering probably also need thus
> > such as ia64, powerpc, and perhaps amd64.  sparc64 already has a barrier.
> >  BTW, it seems that the bus_dma code could be somewhat simplified if
> > there was a sys/kern/subr_busdma.c that contained routines to implement
> > bounce buffers that could be used by the MD code since the MD code that
> > does do bounce pages tends to duplicate a lot of stuff between the
> > different archs.
>
> Indeed it does, and if you want to work on it, please feel free to send
> it to me for
> review.

I can tack it onto my todo list but it'll be buried. :)  I was hoping someone 
else might be able to hack on it and pass it off to you for review. :)

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org