Date: Fri, 02 Mar 2007 09:03:31 -0700 From: Scott Long <scottl@samsco.org> To: Mark Tinguely <tinguely@casselton.net> Cc: current@freebsd.org Subject: Re: multisegment bus_dmamem_alloc() Message-ID: <45E84AD3.7010908@samsco.org> In-Reply-To: <200703021442.l22Eg6QT058195@casselton.net> References: <200703021442.l22Eg6QT058195@casselton.net>
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Mark Tinguely wrote: > Are there any other devices other than bktr(4) that could benefit > from a multisegment bus_dmamem_alloc(9) routine? The old USB system > comes to mind, but I have not studied the new USB. There may be others. > > NetBSD only partially implements this (if the number page allocated > number > of segments, they punt and do a totally contiguous allocation - IMO, they > could fix this pretty easy though). > > I know chages to contigmalloc() is a tricky subject. I was hoping > there are enough drivers that would provide enough merits to change > such an important part of the system. If not, please forgive this noise. > Looking at bktr, it's not at all clear to me why the author felt that FreeBSD didn't support bus_dmamem_alloc. It's even stranger since the author explicitly tells the NetBSD/OpenBSD code to only allocate 1 segment. Meh. I'm getting tired of fighting the busdma API fight with developers who deliberately ignore standard API's that have been around for almost 10 years. Multi-segment bus_dmamem_alloc support would be nice, but bringing the drivers up to API standards would be an even nicer first step. Scotthelp
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