Re: 2.1.111: IDE DMA disabled?

Andrew Derrick Balsa (
Mon, 27 Jul 1998 09:02:51 +0200

Hi Aaron,

On Mon, 27 Jul 1998, Aaron Tiensivu wrote:
>> :-) True. Just as an aside, UDMA is being pushed up to 66MB/s. The newest
>> chipset from VIA already does this, and Intel will probably release new
>> chipsets too. The first ATA-66 drives should appear early in 1999.
>MVP3 or something newer?

Actually, it's a new Southbridge chip that will replace the Southbridge chip in
the present MVP3 chipset. It was developed for their new Slot 1 Northbridge

VIA only provides more details to OEM manufacturers, and like many emails that
have the word "Linux" in them, my request to get a detailed datasheet from them
remained answerless :-(
>> 2) Never had any problems with IBM drives either. I have had almost every sing
>> EIDE model they manufactured: 1.2Gb, 1.7Gb, 2.1Gb, 3.2Gb, 4.3Gb, 6.4Gb, 8.5Gb.
>> All worked flawlessly in DMA mode2 and UDMA on the UDMA capable ones.
>Some early 1.7GB drives had UDMA trouble if driven by a 83mhz bus but
>considering that is REALLY overclocking the drive (and chipset), it's not
>really much on an issue.

IBM drives that can do UDMA are all >= 4.3 Gb. Anything earlier is only DMA
mode2 capable.
>FWIW, I'm running a 6.4G and a 1.7G IBM drive at 83mhz currently with no
>trouble.. ;-)

If you are running your PCI bus at 83MHz/2, you may see random I/O errors.
41.5MHz is beyond specs. You are playing dice with your data, so I assume it
all depends on how much you value it.

If running the PCI bus asynchronously at 33MHz, with the front-side bus (FSB) at
83MHz, you may or may not see problems, depending on your cache RAM and
DIMMs/SIMMs and BIOS chipset timings.


Andrew D. Balsa

- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to Please read the FAQ at