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SubjectRe: [PATCH] Ext.BIOS Translation for AHA-1542
On Sat, Jul 10, 1999 at 04:32:26AM +0200, Andries.Brouwer@cwi.nl wrote:
> > - if(mbenable_result[1] & 0x03) retval = BIOS_TRANSLATION_25563;
> > + if((mbenable_result[0] & 0x08) && (mbenable_result[1] & 0x03))
> > + retval = BIOS_TRANSLATION_25563;
>
> Interesting. As far as I know, the possible values of the pair
> (mbenable_result[0], mbenable_result[1])
> (the two bytes resulting from the CMD_EXTBIOS command; the name is misleading)
> are (0,0), (0,2), (8,1) and (8,2) on a AHA1542CF (or AHA1542CP).
>
> We want BIOS_TRANSLATION_25563 if and only if mbenable_result[0] equals 8.
> So, I think the patch is correct (but needlessly complicated)
> for AHA1542CF. Why do you test `(mbenable_result[1] & 0x03)' ?

That test was already there. I don't know under what circumstances (if
any) it is correct. So I left it in, and added the test which worked under
both the 1542CF and 1542CP controllers I had.

> Last year Nick Andrew compared AHA1542CF with AHA1542CP
> and reported that the second byte equals 2 on a AHA1542CP
> when a big disk is present. Nick - do you recall your precise setup?

Unfortunately I cannot tell you the exact controller revision as things
have been moved around since then. I got annoyed at the unwanted 255x63
geometry and swapped controllers with test kernels until I was satisfied
that my fix was correct.

> Did you have a single disk? And what is `big'?

Yes. The disk is probably a Seagate ST34572N (~4 gigs).

> Did you try to vary b) and c) ?

No.

> I find (0,2) also on AHA1542CF where you only got it on AHA1542CP.

If you like I can pull out a few controllers and test again. I should
have a few spare (soon afterward I "discovered" that the AIC7xxx controller
performance leaves the 1542 series for dead).

Nick.
--
Zeta Internet SP4 Fax: +61-2-9233-6545 Voice: 9231-9400
G.P.O. Box 3400, Sydney NSW 1043 http://www.zeta.org.au/

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