[Bug 556] New: dma not enabled for IDE hard drives

[Martin J. Bligh]

http://bugme.osdl.org/show_bug.cgi?id=556

           Summary: dma not enabled for IDE hard drives
    Kernel Version: 2.5.67
            Status: NEW
          Severity: normal
             Owner: [e-mail]
         Submitter: [e-mail]

Distribution:Debian/Sid

Hardware Environment:dual 2.4Ghz Xeon, SE7500CW2 MB, all Intel
                      Promise PDC20267 ATA-100 ide channels in
                      non-RAID mode

Software Environment:testing with hdparm 5.2-1 of Debian/Sid

Problem Description:

I have similar .config settings for both the 2.4.20 and the 2.5.67
kernels with the identical machine.  Under 2.4.20, I do get dma enabled 
and see good performance (Mb/s) from the hard disk I/O.  

However, under the 2.5.67 kernel, dma is not enabled and the performance 
of the hard drives is poor (~2-3 Mb/s under 2.5.67 versus ~30 Mb/s under 
2.4.20).  The "hdparm -I /dev/hda" command confirms that dma is 
enabled on the hardware, but "hdparm -d1 /dev/hda" confirms that dma will not
enable and the performenace is poor under 2.5.67.  Under 2.4.20, these same
commands show good performance.

Steps to reproduce:

make the kernel, run lilo, boot, and run hdparm tests on this machine.