Date: Tue, 14 Jun 2005 02:50:24 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: "M. Warner Losh" <imp@bsdimp.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Obvious bug in /sys/i386/include/bus.h Message-ID: <200506140250.26275.hselasky@c2i.net> In-Reply-To: <20050613.172307.81090793.imp@bsdimp.com> References: <200506131412.38967.hselasky@c2i.net> <20050613.172307.81090793.imp@bsdimp.com>
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On Tuesday 14 June 2005 01:23, M. Warner Losh wrote: > In message: <200506131412.38967.hselasky@c2i.net> > > Hans Petter Selasky <hselasky@c2i.net> writes: > : So can someone have this fixed, or is there a reason not to fix it. The > : one who wrote the code has done the same mistake with every one of the > : bus_space_XXXX that does memory mapped I/O. It currently breaks my > : drivers. > > One isn't supposed to call these routines with count == 0. One could > say your drivers are broken :-) > > Back when these were written, small optimizations like this were made > to make things go faster. Now that cache sizes are bigger, a few > extra instructions likely wouldn't affect things too much. Best to > measure the effects of your proposed changes on real workloads... These functions are used to move smaller amounts of data. Larger amounts of data should be moved using DMA. In this case functionality is more important than performance?! -- HPS
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