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From: | Jason Brittain |
Subject: | Re: [Qemu-devel] enabling bus-master IDE driver |
Date: | Fri, 05 Nov 2004 17:53:01 -0800 |
User-agent: | Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20040913 |
zitu wrote:
Quoting zitu <address@hidden>:Does that mean that the patch doesn't work? Do I have to do something else to make dma work?I think this patch is almost complete for linux and solaris guests. Some more work/init is needed inside XP/NT/2K. Anyone around with this knowledge ?answering to myself... :) WIN_WRITEDMA_EXT & WIN_READDMA_EXT cases are not defined in hw/ide.c I have no idea where to start to write a patch for these... :( Until these and the atapi_dma are set/defined, no dma should work IMHO. And this seems not to be OS dependant. Which means the linux figures I got were wrong ???
My Linux (kernel 2.6) guest's disk seems slow too. I applied the DMA patch, and at first it seemed faster (it may be a bit faster). But, I tried using hdparm -d1 /dev/hda to make sure DMA was turned on in the guest Linux and it said: /dev/hda: setting using_dma to 1 (on) HDIO_SET_DMA failed: Operation not permitted using_dma = 0 (off) So I'm pretty sure DMA doesn't work with this patch even with a Linux guest -- at least in my setup. -- Jason Brittain
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