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Date:      Thu, 15 Sep 2005 15:22:37 -0400
From:      John Baldwin <jhb@FreeBSD.org>
To:        Scott Long <scottl@samsco.org>
Cc:        cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/alpha/alpha busdma_machdep.c
Message-ID:  <200509151522.39043.jhb@FreeBSD.org>
In-Reply-To: <4329C835.6020104@samsco.org>
References:  <200509151709.j8FH9hkm099887@repoman.freebsd.org> <200509151341.42862.jhb@FreeBSD.org> <4329C835.6020104@samsco.org>

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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@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org



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