[uClinux-dev] BDM operational oddities

Bruce Paterson bruce at tele-ip.com
Thu Nov 1 23:38:33 EST 2001

Bruce Paterson wrote:
> > Is the console printing anything? I did not write this code, M. Leslie
> No. It seems it's the low level driver used at startup that is hanging.

OK. Some success at last !
I tracked it down by going through all the registers required for the
SMC1 to work one
by one till I found what was wrong. It was pretty obsure.

The code in arch/m68knommu/kernel/setup.c assumed an oscilator prescaler
of 128 prior to
the PLL, whereas our card doesn't use the prescaler. I hard coded it for
now removing the /128, but
a better fix would be to look at the prescaler bit in the pll register
and apply the appropriate
division. Thsi wrong value for the system_clock resulted in a rubbish
(-ve) value for the Baud
rate generators in BRG0 (for SMC1).

Now I get the text at last. yay !!

Problem is, I crash out with:
Ramdisk driver initialised: 16 ramdisks of 4096K size
Blkmem 0 disk images:
arena open of 0 failed
VFS: cannot open root fs (1f:00)

I'm using the mleslie supplied romfs.img and 2.0.38 kernel (for now). I
have _ramfs setup at
0x99000 in RAM (instead of immediately after the text section) since
it's easier for me to
manipulate the s19 files at the moment.
I'm using "make linux.s19", "make romfs.s19", editing the 2 together to
make a single s19 file
that is d/l using bdm (or the bootrom using tftp).
The romfs does end up at 99000 as required as I can see "-rom1fs-" there
using gdb.
It also says that location = _ramfs, which I think is correct.

I'll start looking at the fs code, but anyone got a better idea where I
should go from here ?

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