Re: VAX port internals etc...

[Holm Tiffe <holm%freibergnet.de@localhost>]

Anders Magnusson wrote:

> On 01/24/2013 03:13 PM, Holm Tiffe wrote:
> >Anders Magnusson wrote:
> >
> >>Hi Holm et al,
> >[..]
> >>So, any more questions that I have missed in the massive mail
> >>conversations that has been last week? :-)
> >>
> >>-- Ragge
> >At least one Question I have curently..
> >
> >You wrote in a post before I should disable that rebooting after an HALT
> >for debugging purposes... hmm tried that, w/o much luck.
> >
> >There are 12 dip switches on that board (not 8 like I wrote before) and I
> >tried to disable that but it doesn't work.
> >
> >If I power up the machine the value BOOT is empty (...) and HALT is set to
> >0x03 which should be correct.
> >If I boot netbsd and it runs on a halt instruction that thing reboots,
> >BOOT ist then set to eza0 and HALT to 0... and that damn thing is
> >rebooting.
> >
> >Is it possible that the values somewhere in the RMA are overwritten from
> >the Firmware itself or from some netbsd code? What could I try further to
> >disable this reboots?
> The action that should be taken on halt is usually defined in something 
> called the console mailbox.
> The rt300 seems to use ordinary memory for this, therefore it may be 
> overwritten.  Look at
> section 4.8.1.2 in the manual about this.
> 
> -- Ragge

Hmm, yes I read that, but interestingly there is nowhere defined wich
memorey area that is, only that the console mailbox is at Offset 0 in the
"scratch memory area which is marked "bad" in the memory bitmap to prevent
higher-level software from modifying their data indescriminately"

It seems that NetBSD is doing his own thing here and is sizing the memory for
itself...

Below the Console Mailbox Register bit description (Figure 4-7) is a line
"MLO-004503", below the Display and Uart Status register decription
"MLO-004504". Is that possibly an Offset to something?

I think it is generally possible to map out such memory locations from
NetBSD use if I know where this area is. I'll try to find out where ans
will asking later how to implement this "mapping out" ...

Regards,

Holm

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