Startup: "DMA disabled" on VIA vt82c686b IDE UDMA100, Kernel 2.5.38

[Stephan Maciej <stephan@maciej.muc.de>]

Greetings,

I just managed to compile and boot a 2.5.38 kernel on my Sony Vaio Laptop. I 
run the kernel for about half an hour now, XWindows, KDE working fine, even 
my USB mouse is working --  but I can't use my touchpad in parallel... :-(

Nevertheless, great work so far. But I have found this in my startup dmesg:

Uniform Multi-Platform E-IDE driver Revision: 7.00alpha2
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
VP_IDE: IDE controller at PCI slot 00:07.1
VP_IDE: chipset revision 6
VP_IDE: not 100% native mode: will probe irqs later
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
VP_IDE: VIA vt82c686b (rev 40) IDE UDMA100 controller on pci00:07.1
    ide0: BM-DMA at 0x1c40-0x1c47, BIOS settings: hda:DMA, hdb:pio
    ide1: BM-DMA at 0x1c48-0x1c4f, BIOS settings: hdc:DMA, hdd:pio
hda: HITACHI_DK23CA-20, ATA DISK drive
hda: DMA disabled
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
hdc: QSI DVD-ROM SDR-081, ATAPI CD/DVD-ROM drive
hdc: DMA disabled
ide1 at 0x170-0x177,0x376 on irq 15
hda: host protected area => 1
hda: 39070080 sectors (20004 MB) w/2048KiB Cache, CHS=2432/255/63, UDMA(100)
 hda: hda1 hda2 hda3
hdc: ATAPI 61X DVD-ROM drive, 512kB Cache, UDMA(33)

[ Ahem, well, my DVD ROM drive was supposed to be 24x CD/8x DVD, but that's 
okay. ]

/proc/ide/via says that my HD is running UDMA100 and my 61x ;-) DVD-ROM runs 
UDMA33. As a hdparm -t -T tells me about 150Mb/sec throughput (buffered) and 
20Mb/sec (disk) reads, I suppose BMDMA is really on.

Why does this message appear then?

Stephan

-- 
"That's interesting.  Can it be disabled?" -- someone on LKML, after being 
told about the PIV hyperthreading features