Date: Mon, 18 Aug 1997 04:34:18 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: smp@csn.net (Steve Passe), luigi@labinfo.iet.unipi.it (Luigi Rizzo) Cc: multimedia@freebsd.org, hackers@freebsd.org Subject: isa_dmastatus Message-ID: <199708180234.EAA09705@labinfo.iet.unipi.it> In-Reply-To: <199708180245.UAA09140@Ilsa.StevesCafe.com> from "Steve Passe" at Aug 17, 97 08:44:41 pm
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Feeling much involved with this issue... I fully second Steve's opinion and with the same motivations: > people realize that the days of different pieces of code accessing common > hardware are over. As SMP is brought into more and more of the kernel this > becomes unacceptable. Areas such as the DMA hardware will have to be > encapsolated into "critical regions". No one will be allowed to have private > code to access these sorts of things, not even for short testing periods. this said, and since I cannot track very easily -current and amancio's work, I cannot say from here what in the committed isa_dmastatus conflicts with guxpnpXX. I saw once a comment related to the voxware code not following the proper sequence of calls to the dma functions thus having problems with checks for dma_inuse and dma_busy. Having been there I have the feeling that it would be a pain in the neck to make the voxware code behave properly, and the easiest workaround is to disable such checks. My code does not have these problems but I had the advantage of starting from scratch, so I decided to put the checks in as an additional safety mechanism, and since they did not harm for me. Pragmatically, I suggest that at least temporarily the isa_dmastatus be made to work for guspnpXX. After all the sound driver (guspnpXX, or mine) is the only part of the system using it at the moment, I don't think Amancio is asking for changes to the interface of the function, and disabling some checks does not change the function's behaviour when invoked in the correct way. Cheers Luigi -----------------------------+-------------------------------------- Luigi Rizzo | Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it | Universita' di Pisa tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ _____________________________|______________________________________
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