Re: netboot loader not closing devices

[Felix Deichmann <m4j0rd0m0%gmail.com@localhost>]

2015-06-07 4:11 GMT+02:00 Charles Dickman <chd%chdickman.com@localhost>:
> The bootloader doesn't know about the DMA map and so boot and the
> kernel have to fit in the area mappable and starting at 0x00000000.

Looking at the KA670 Technical Manual, section E for example, the SG
DMA map after power-up is setup by firmware such that it maps to the
first 4 MB of main memory, *except* for pages marked bad by the PFN
bitmap, and *except* for corresponding pages in Q22 memory. I guess
this is the same for other Q-Bus machines with CQBIC.

So if our bootloader on such machines used the information in the
Q-Bus Map Registers (if available) and maybe the PFN bitmap in
addition it could skip occupied (and bad) memory reliably? Would also
help with a VCB01, right?

> I also have a KZQSA I have been wanting play with. It has a memory buffer too.

Do you also expect the KZQSA to be equally limited with NetBSD as with VMS?
AFAIK, only a very small amount of devices worked with it (specific
"slow" ones) or was officially supported unfortunately, due to
hardware/timing limitations. Would have been the desired Q-Bus-to-SCSI
adapter otherwise...
http://h71000.www7.hp.com/wizard/wiz_9254.html

Felix