Date: Sun, 16 Oct 2011 12:39:21 +0800 From: Adrian Chadd <adrian@freebsd.org> To: Warner Losh <imp@bsdimp.com> Cc: freebsd-arch@freebsd.org Subject: Re: newbus bus access routines and bus_space_barrier() Message-ID: <CAJ-VmonEAiosgJNLU75OFWzOk8CsshBOT_H7WcWKp%2B5VKFsRrA@mail.gmail.com> In-Reply-To: <4EEA1F8B-9854-4C5C-A397-95AD454D3680@bsdimp.com> References: <CAJ-VmonJnHyLQJ-kVtMV=X7mq7=wq2MGn9wUqdbEtZ6qXd52rg@mail.gmail.com> <4EEA1F8B-9854-4C5C-A397-95AD454D3680@bsdimp.com>
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On 16 October 2011 11:45, Warner Losh <imp@bsdimp.com> wrote: > Usually they are needed, but we get away without them often because they are needed in a limited set of circumstances and we have memory barriers in our locking primitives. Right. I'll just change the ath driver register ops to enforce a read/write barrier on each read or write. It'd be nice to teach the driver and the HAL about "correct" barriers but I just don't have the time. :( (FYI: apparently linux's ioread32/iowrite32 operations enforce barriers on each op.) Adrian
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