[comp.os.minix] Extended Memory trouble on a VAXmate

bengtb@erix.UUCP (Bengt Baeverman) (08/22/87)

I have now successfully installed version 1.2 of MINIX on a Digital
Equipment VAXmate, which is a PC/AT clone. When I got the AT distribution
is was easy.

I wonder why the patches for loading the RAMdisk into extended memory
does not work. Digital has provided a RAMdisk drive for MSDOS and it
becomes 256KB, so it can be done!

The symptoms are: When booting everything looks OK. It starts loading
the data from the root floopy into extended memory (or at least it says
so). When all 256 KB has been loaded it tells me everything has been loaded
and that I can remove the root file system floppy. The it continues with 
adding:

File system panic: Root file system corrupted. Possibly wrong diskette.

If I take the same boot-floppy and try with another, smaller, root-floppy
it all works like a dream. When I use a version of MINIX 1.2 without these
patches and use the 256KB root-floppy it also works OK. 

My conclusion is that there is something odd with the memory map on the
VAXmate. Could you please explain how extended memory should work and ,if 
you known anything about the VAXmate -- tell me how IT works. 

BTW: I could not find the '.word xxxx' in klib88.s that the comment to
xm_xfer() talks about. I tried the patches previously published adding
the words after the INT 0x15 instruction (using .byte 0x9a instead of
int 0x15).

			Bengt Baverman
			bengtb@erix.se