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 From:  Frederick Page <fpage at thebetteros dot oche dot de>
 To:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] SOLUTION: "Panic" while booting net4801
 Date:  Mon, 26 Jul 2004 02:23:26 +0200
Hallo Mitch,

Mitch (WebCob) schrieb am 25. Juli 2004:

>>But the cause is the ATA driver in FreeBSD, which does not always
>>correctly identify the hardware capabilities.

As I said: I am a *BSD newbie and that's what Google told me.

>>(...) the CF card was (wrongly) addressed/recognized as WDMA2.

>Forgive the possibly dumb question, but how would anyone know WDMA2
>was wrong?

DMA (Direct Memory Access) is a better/faster way to access hardware,
but it's also less compatible as the elderly PIO (Peripheral Input
Output). And since my correctly working microdrive was addressed as
PIO3, it didn't take much of a rocket-scientist to figure out, that
the WDMA2 caused the problem. WDMA2 also was in each and every
problem-mail in the mailing-list.

>Or does it depend on the drive having an intelligent controller to
>manage the DMA?

It depends on the drive. Most modern harddrives can do (Ultra)DMA, but
CF-cards are "simulated" harddrives, they behave like HDs. m0n0wall
uses an elderly FreeBSD 4.9 (I'm sure for good reasons), but the ATA
driver is not as advanced as in recent FreeBSD releases.

Since m0n0wall is often used with elderly hardware, I think
compatibility is much more important than the speed of the 6 MB
boot-medium. No more need to try different brands of CD-rom or

>Someone should post the information to a BSD list so they know the

I found out about the problems of the ATA driver on those lists, the
problem is known and recent FreeBSD ATA drivers are improved.

>Manuel may be interested in watching it for when a corrected kernel /
>boot loader comes out.

I can only suggest to deactivate DMA in upcoming m0n0wall releases.
It's up to Manuel and the developers.

>to prevent this from recurring when people such as yourself update
>the firmware.

I was lucky enough to have a notebook with OpenBSD 3.5 at hand, also
have a PCMCIA adapter. (Didn't have FFS filesystem support on my

>Like you say, a 6MB os hardly needs DMA - maybe we should make the
>default off until the detection works properly?

This would be a good idea (IMHO). Maybe someone has his previously
non-working old CD-Rom or CF-card still in a drawer and is willing to
try again with DMA switched off?

One could try and search the mailing-list for just "WDMA2" and find
lots of problem-issues, that (IMHO) more than justify setting the
defaults to PIO.

Kind regards