lkml.org 
[lkml]   [1998]   [Oct]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
Subject(U)DMA Explained (Re: Kernel freeze on boot (.123-.125) in IDE init)
On Wed, 21 Oct 1998, Daniel Nash wrote:

> hda: IBM-DAQA-33240, 3098MB w/96kB Cache, CHS=787/128/63, DMA
> hdb: WDC AC31600H, 1549MB w/128kB Cache, CHS=787/64/63, DMA

First Question:

Are IBM-DAQA-33240 and WDC AC31600H are UDMA by default???

If they are, you need to move them off the 430HX PIIX3.
This silly controller thinks that it can do UDMA, because it can decode
the difference in the hardware. However, you would have seen (U)DMA if
you could turn off in the BIOS timing settings.

What is the mainboard nad bios revision?

> hde: IBM-DHEA-38451, 8063MB w/472kB Cache, CHS=16383/16/63, UDMA

There are now three DMA reporting states of IDE-devices.

A trailing tag with UDMA is considered, 100% native.
A trailing tag with (U)DMA is considered, native capable (forgot to enable)
A trailing tag with DMA is considered, straight Multi/Single Word native.

There are currently no reporting point to date that report the mode level.
That is DMA can be DMA mode 2/1/0 as multi or single word, thus 6 possible
mode levels are blanketed under this trailing TAG. Note that (U)DMA is
reverted to any of these mode levels, also. UDMA will be UDMA mode 2/1/0,
thus 3possiblemode levels are blanketed under this trailing TAG.

Cheers,
Andre Hedrick
The IDE-FNG for Linux
The APC UPS Specialist for Linux

http://www.dyer.vanderbilt.edu/server/udma/
http://www.dyer.vanderbilt.edu/server/apcupsd/ SUSPENDED



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:45    [W:0.371 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site