Port-vax archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: anyone know what's going on in dw780_errchk



Anders Magnusson wrote:
Johnny Billquist wrote:
Anders Magnusson wrote:
Johnny Billquist wrote:
Brad Parker wrote:
I seem to have my foot stuck in a gopher hole.  I'm confused about a
few things.

- the hp.c driver in boot/ ignores the partition argument (making it
impossible
to boot a miniroot I think).  fortunately the other drivers in boot/
(ra & mfm)
do honor the partition arg.

- if one does get a miniroot kernel to boot, the partition info is not
communicated to the new kernel.  so it thinks you booted from
partition 0
('a') and uses that as root.  rather confusing.

am I correct about that?

4.3bsd sends the boot partition in r10.  It seems like using one of the
"rpb" registers (like r4) might be a better plan.  Is there any reason
not to send the boot partition info in r4?  (i.e. rpb_bootr4)

other platforms (1-2 anyway) seem to use MAKEBOOTDEV()
Not sure how much we care, but VMB have reserved meanings for R0-R5,
which we would break by this idea.

It shouldn't matter here, this code is executed long after VMB is left
:-)
Hey. If I need to set R4 to a specific value to make VMB happy, I can't
really set it to something else to make boot happy, can I?

Eh, of course :-/

Hm, I don't think Ultrix can give partition number, can it?  If it can, we
should use the same way, otherwise it would be backward-compatible to
encode it in the upper word of R3 maybe?  Or use R4, the comment in your
boot file says that it is only used if R5 bit 3 is set.

And R5 bit 3 is set in my boot file, if you look. :-)

No, Ultrix can't specify a specific partition, as far as I know.
I wonder if VMB really appreciate that we stuff something in the high bits of R3?

If I were to suggest anything, it would be to use a few bits of R5. VMS do that to select the root directory for the boot. So that should be pretty harmless. And VMS use four bits for that, which would give us 16 partitions. ([SYS0] to [SYSF] in VMS) I don't remember for sure, but I think it's the four high bits of R5 that is used for this?

        Johnny

--
Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt%softjar.se@localhost             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol


Home | Main Index | Thread Index | Old Index