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Re: [Qemu-devel] enabling bus-master IDE driver

From: Jason Brittain
Subject: Re: [Qemu-devel] enabling bus-master IDE driver
Date: Sat, 06 Nov 2004 23:12:38 -0800
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20040913

zitu wrote:
Quoting James Boddington <address@hidden>:

James Boddington wrote:

I found 2000 is using pio as well.

I'll change that. It is with 2000 + sp4. I am getting pio on the primary
ide and dma on the secondary ide channel.

on xp, it's PIO for both. DMA if available only on primary (hdd).

For linux guest, as root, hdparm -d0/-d1 doesn't work.

But with the DMA patch, you should see DMA is on with the following:
'hdparm /dev/hda'
It's also visible in /proc/ide/hda/settings :)

Looks like mine (with the patch) shows DMA is off:

 multcount      = 16 (on)
 IO_support     =  0 (default 16-bit)
 unmaskirq      =  0 (off)
 using_dma      =  0 (off)
 keepsettings   =  0 (off)
 readonly       =  0 (off)
 readahead      = 256 (on)
 geometry       = 33288/16/63, sectors = 33554432, start = 0

And, I can set the IO_support to 1 with hdparm -c1 /dev/hda,
but, as you say, I can't set using_dma to 1 with
hdparm -d1 /dev/hda.  So, looks like it's off, and I can't turn
it on.  Should the IO_support = 1 help any with disk performance?
It doesn't appear to.

Jason Brittain

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