I have a computer with the following lspci output:
root@debian:~# lspci
00:00.0 Host bridge: Intel Corporation 82852/82855 GM/GME/PM/GMV Processor to I/O Controller (rev 02)
00:00.1 System peripheral: Intel Corporation 82852/82855 GM/GME/PM/GMV Processor to I/O Controller (rev 02)
00:00.3 System peripheral: Intel Corporation 82852/82855 GM/GME/PM/GMV Processor to I/O Controller (rev 02)
00:01.0 PCI bridge: Intel Corporation 82852/82855 GM/GME/PM/GMV Processor to AGP Controller (rev 02)
00:02.0 VGA compatible controller: Intel Corporation 82852/855GM Integrated Graphics Device (rev 02)
00:1d.0 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 02)
00:1d.1 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 (rev 02)
00:1d.7 USB Controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2 EHCI Controller (rev 02)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 82)
00:1f.0 ISA bridge: Intel Corporation 82801DB/DBL (ICH4/ICH4-L) LPC Interface Bridge (rev 02)
00:1f.1 IDE interface: Intel Corporation 82801DB (ICH4) IDE Controller (rev 02)
00:1f.3 SMBus: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) SMBus Controller (rev 02)
00:1f.5 Multimedia audio controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio Controller (rev 02)
02:04.0 Ethernet controller: Intel Corporation 8255xER/82551IT Fast Ethernet Controller (rev 10)
02:05.0 Ethernet controller: Intel Corporation 8255xER/82551IT Fast Ethernet Controller (rev 10)

The problem is that in my dmesg I get the following lines from the my IDE controller driver:
ICH4: IDE controller at PCI slot 0000:00:1f.1
ICH4: chipset revision 2
ICH4: not 100% native mode: will probe irqs later
ide0: BM-DMA at 0xdc00-0xdc07, BIOS settings: hda:pio, hdb:pio
ide1: BM-DMA at 0xdc08-0xdc0f, BIOS settings: hdc:pio, hdd:pio
Probing IDE interface ide0...

Everything above looks fine except that BIOS settings shows that my IDE devices are in PIO mode but when I try to print out the information from hdparm it seems that it is using the UDMA mode 5 which is the correct expected behaviour.
Here are some outputs from hdparm:

root@debian:~# hdparm -i /dev/hda

/dev/hda:

Model=WDC WD800BB-22JHC0, FwRev=05.01C05, SerialNo=WD-WMAM95758510
Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=66
BuffType=unknown, BuffSize=2048kB, MaxMultSect=16, MultSect=off
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156301488
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
AdvancedPM=no WriteCache=enabled
Drive conforms to: Unspecified: ATA/ATAPI-1 ATA/ATAPI-2 ATA/ATAPI-3 ATA/ATAPI-4 ATA/ATAPI-5 ATA/ATAPI-6

* signifies the current active mode

root@debian:~# hdparm /dev/hda

/dev/hda:
multcount = 0 (off)
IO_support = 0 (default 16-bit)
unmaskirq = 0 (off)
using_dma = 1 (on)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 256 (on)
geometry = 65535/16/63, sectors = 156301488, start = 0
root@debian:~#

and finally the performance test:
root@debian:~# hdparm -tT /dev/hda

/dev/hda:
Timing cached reads: 2004 MB in 2.00 seconds = 1003.95 MB/sec
Timing buffered disk reads: 170 MB in 3.03 seconds = 56.07 MB/sec
root@debian:~#

All the above 3 output indicates that my IDE Hard drive is in UDMA mode.

So why do I get the following message in the dmesg output????
ide0: BM-DMA at 0xdc00-0xdc07, BIOS settings: hda:pio, hdb:pio
ide1: BM-DMA at 0xdc08-0xdc0f, BIOS settings: hdc:pio, hdd:pio

Does it mean that although the BIOS shows that it is in PIO mode the linux kernel is overriding that fact and uses the DMA mode. I want to use the DMA mode too but because the outputs were conflicting I got confused. I have verified my BIOS settings and UDMA for the Primary and Secondary controller are enabled.

Any clues?

Thanks