I running debian linux on an old box on which I just built 2.6.6. The manufacturer lists the chipset as:

AMD 750, consisting of the AMD 751 Irongate North bridge and the AMD 756 Viper South bridge

I am trying to enable DMA for the harddrive with no luck. I get the output:

/dev/hda:

setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)

Most posts regarding this say that this happens when the chipset drivers are not built into the kernel. However, I have been unable to find this chipset in the kernel config. The only place it seems to show up is under apgart options, which doesn't help. The drive is IDE and the only drive on the cable. It is jumpered to Cable Select. Any ideas about how to fix this? Thanks!

Here's the output of lspci in case it helps:

0000:00:00.0 Host bridge: Advanced Micro Devices [AMD] AMD-751 [Irongate] System Controller (rev 25)
0000:00:01.0 PCI bridge: Advanced Micro Devices [AMD] AMD-751 [Irongate] AGP Bridge (rev 01)
0000:00:07.0 ISA bridge: Advanced Micro Devices [AMD] AMD-756 [Viper] ISA (rev 01)
0000:00:07.1 IDE interface: Advanced Micro Devices [AMD] AMD-756 [Viper] IDE (rev 07)
0000:00:07.3 Bridge: Advanced Micro Devices [AMD] AMD-756 [Viper] ACPI (rev 03)
0000:00:07.4 USB Controller: Advanced Micro Devices [AMD] AMD-756 [Viper] USB (rev 06)
0000:00:11.0 Communication controller: Conexant HCF 56k Data/Fax/Voice/Spkp Modem (rev 08)
0000:00:12.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)
0000:00:13.0 Multimedia video controller: Internext Compression Inc iTVC16 (CX23416) MPEG-2 Encoder (rev 01)
0000:00:14.0 Multimedia audio controller: Ensoniq ES1371 [AudioPCI-97] (rev 08)
0000:01:05.0 VGA compatible controller: nVidia Corporation NV18 [GeForce4 MX 4000 AGP 8x] (rev c1)

This was a silly mistake... I didn't enable 'PCI IDE chipset support' in the kernel, and thus my chipset didn't appear.