Date: Thu, 27 Oct 2005 13:47:59 +0800 From: Dinesh Nair <dinesh@alphaque.com> To: Scott Long <scottl@samsco.org> Cc: freebsd-hackers@freebsd.org Subject: Re: correct use of bus_dmamap_sync Message-ID: <43606A0F.5000704@alphaque.com> In-Reply-To: <435FE416.1050703@samsco.org> References: <435E3003.4050609@alphaque.com> <200510251610.53127.jhb@freebsd.org> <435F1E77.30007@alphaque.com> <200510261320.16175.jhb@freebsd.org> <435FE416.1050703@samsco.org>
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On 10/27/05 04:16 Scott Long said the following: >>> an example would be using (BUS_DMASYNC_POSTREAD|BUS_DMASYNC_PREWRITE) >>> which >>> would be 0x03 in freebsd 4.x and 0x06 in freebsd 5.x. the gotcha is that >>> 0x03 in freebsd 4.x is BUS_DMASYNC_POSTWRITE. so therefore, >>> BUS_DMASYNC_POSTREAD|BUS_DMASYNC_PREWRITE will be >>> BUS_DMASYNC_POSTWRITE in >>> 4.x which in the syscall is actually a no op. >> >> Yes, that is fugly. Just don't use the | versions for now I would guess. > > Trying to maintain source compatibility between 4.x and 5.x/6.x will > make you encounter a whole lot more problems than just this. could you elaborate on what busdma related problems there'd be, between 4.x and 5.x/6.x ? do, for example, the inner workings of the bus_dma* syscalls work the same on both ? -- Regards, /\_/\ "All dogs go to heaven." dinesh@alphaque.com (0 0) http://www.alphaque.com/ +==========================----oOO--(_)--OOo----==========================+ | for a in past present future; do | | for b in clients employers associates relatives neighbours pets; do | | echo "The opinions here in no way reflect the opinions of my $a $b." | | done; done | +=========================================================================+
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