Re: anyone know what's going on in dw780_errchk

[Anders Magnusson <ragge%ludd.ltu.se@localhost>]

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.

-- Ragge