[Xen-devel] Problems with DMA in xen0

[Matthias Hofherr <matthias_hofherr@xxxxxxxx>]

Hi list,

I'm doing currently some tests with xen in order to migrate a development 
environment from User Mode Linux to Xen. So far, Xen looks very promising.
My only problem currently is that my xen0 kernel seems no to be able to use 
DMA modes for hard disk access.

With the xen0 kernel (2.6.8.1), hdparm shows me
  hdparm -t /dev/hda
  /dev/hda:
  Timing buffered disk reads:   10 MB in  3.08 seconds =   3.25 MB/sec
When I boot with a standard non-Xen kernel (2.6.7), I get about 52 MB/sec.
In both kernels support for my Intel boad Chipset () is enabled.
When I try to set DMA with hdparm manually:
 hdparm -u1 -d1 -X66 -m 16 -c 3 -W 1 /dev/hda
/dev/hda:
 setting 32-bit IO_support flag to 3
 setting multcount to 16
 setting unmaskirq to 1 (on)
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 setting xfermode to 66 (UltraDMA mode2)
 setting drive write-caching to 1 (on)
 multcount    = 16 (on)
 IO_support   =  3 (32-bit w/sync)
 unmaskirq    =  1 (on)
 using_dma    =  0 (off)

I'm using the nightly snapshot tarball xen-unstable from yesterday. 
Any ideas what's the problem ?

Regards,

Matthias Hofherr

-- 
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 Matthias Hofherr             EMail: Matthias_Hofherr@xxxxxxxx
 GeNUA Gesellschaft fuer Netzwerk- und Unix-Administration mbH
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