[help] how force grub to disable UDMA2?

[acrux]

Hi to all,

i've really read the chapter Reporting bugs in your document and i've a question for You.

 

I am running MK 8.2 on an AOpen AX6BC mobo with FSB overclocked address@hidden. The mobo design is several
years old and doesn't have the possibility to set PCI bus speed but it supports at last UDMA-33 on both on-board IDE controllers.

I have a Maxtor DiamondMax Plus 2500 UDMA-33 7.2GB drive (model  90750D6) where is installed my distro. This HDD is known to be unable keeping a FSB over 103MHz.

E.g. MS Windows (if installed) doesn't boot at 112MHz and UDMA33 enabled but boots only if in the bios i disable the UDMA and i set it to PIO4.

 

With linux during bootup the system freezes or very very seldom it waits for four (4) DMA timeouts then  disables DMA and then mounts the filesystem.

 

I read the Ultra-DMA mini HOWTO and didn' t find anything that looked helpful 'cause the hdparm-4.9 doesn't keep the PIO MODE 4 after a reboot and so i'm unable to keep my system overclocked in linux.

I disabled DMA in the BIOS but that didn't change anything -- linux does a bypass of CMOS settings and enables the UDMA ( and the ACPI function too) and obviously freezes.

 

I want to know haw to set GRUB - if it's possible - to force linux to use this HDD like a PIO4 (as well as bios settings) and not like a UDMA33.

 

TIA

 

Acrux

Napoli, Italy