[655] in linux-scsi channel archive
Re: How to hange NCR 53c810 bus ID ?
daemon@ATHENA.MIT.EDU (Matthias Urlichs)
Wed Oct 4 14:23:13 1995
From: urlichs@mail.noris.net (Matthias Urlichs)
To: eowmob@exp-math.uni-essen.de
Date: Wed, 4 Oct 1995 13:19:03 +0000 (MET)
Cc: drew@poohsticks.org, urlichs@smurf.noris.de,
submit-linux-dev-scsi@ratatosk.yggdrasil.com
In-Reply-To: <Pine.3.89.9510041210.A49359-0100000@werner.exp-math.uni-essen.de> from "Michael Weller" at Oct 4, 95 12:44:21 pm
Hi,
>> >Find this line
>> >
>> > host->this_id = NCR53c7x0_read8(SCID_REG) & 7;
>> >
>> >in NCR53c7x0_init and change the right side to whatever value you want to
>> >use.
>> >
>> Tried that already. Result: a crash; the system doesn't boot.
>
>Well, I didn't look in the driver.
I did..:
>
>If you want to change the id yourself in the scsi driver you'll certainly
>have to reprogram the NCR. Writing to the lower 3 bits of above NCR
>register seems sensable if no docs are available.
This is exactly what the driver ends up doing later.
Unfortunately that doesn't seem to be enough.
>when the bios uses another id during bootup as it may (does if you boot
>from scsi) touch the bus and will confuse the other machine (I remember
>you wanted to connect a linux machine to a mac or something).
>
Since there really shouldn't be any outstanding request at the time of the
switch, this is not a problem.
I might have to make sure that the Mac is powered down (or at least idle)
when the Linux box boots, but that shouldn't be a problem. If all else
fails I'll connect it behind one of the relays behind the microcontroller
I'm planning to use for general supervision and remote-reset-button-pushing.
>Keep also in mind that problems occur when both system access the same
>devices.
I know. Won't happen. (At least, not initially.)
--
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