Messages in this thread |  | | Date | Fri, 21 Sep 2001 14:45:06 -0400 | From | Thomas Hood <> | Subject | Re: [PATCH] parport_pc.c PnP BIOS sanity check |
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Thanks for the replies.
I'd like to underline Alan Cox's reply that DMA0 _is_ usable. In fact, my sound chip is configured to use DMA0.
If (and only if) parport _cannot_ use DMA0 for some reason then the sanity check is justified. In that case I'd just ask that a short comment be added to the code that gives the reason.
Cheers Thomas
Ignacio Vazquez-Abrams wrote: > DMA0 is reserved for memory refresh. It _can't_ be used for anything else, > therefore a value of 0 is representative of no value whatsoever.
Alan Cox wrote: > This has been unsafe since about 1995, when DMA 0 became available as PC's > stopped using the ISA DMA engine for memory refresh (a very neat original PC > hack)
Gunther Mayer wrote: > 1) > I think I saw some BIOS report DMA0 for "none" (could even have > been ACPI which is returning PNP formatted legacy resource data). > 2) > I have never seen DMA0 for parport configured by a BIOS. > 3) > Try "lssuperio" if you want the real hardware thing. > > This qualifies the code as it is as a sanity check. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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