Messages in this thread | | | Date | Wed, 24 Sep 2003 16:25:47 +0000 | From | Adam Belay <> | Subject | Re: [PATCH] PnP Fixes for 2.6.0-test5 |
| |
On Mon, Sep 22, 2003 at 12:32:15PM +0100, Alan Cox wrote: > On Sul, 2003-09-21 at 21:11, Adam Belay wrote: > > # -------------------------------------------- > > # 03/09/21 ambx1@neo.rr.com 1.1357 > > # [PNP] remove DMA 0 restrictions > > # > > # The original argument for blocking DMA 0 was to avoid conflicts with > > # "memory refresh" but such configurations are only found on very old > > # 8-bit systems that are likely not supported by the linux kernel. > > DMA0 is used by lots of 386/486 era systems for memory refresh. It is > also "borrowed" by some other systems that know it isnt available to the > OS. There are a couple of heuristics I've seen suggested by vendors of > things like sound cards > > 1. Check the PnPBIOS information (never looked into this myself)
Assuming the PnPBIOS provides this information through device nodes, the current pnp code will ensure that dma 0 is not used.
> 2. Assume DMA 0 is free if the machine has a PCI bus detected > 3. Read the DMA 0 counter a few times. If it is continually changing > don't use DMA 0 > > #2 is certainly a good idea IMHO, I don't know how well the others work.
Thanks, I'll look into these further.
Regards, Adam - 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/
| |