On Sat, 22 May 2021, BALATON Zoltan wrote:
On Sat, 22 May 2021, Alexey Kardashevskiy wrote:
VOF itself does not prints anything in this patch.
However it seems to be needed for linux as the first thing it does seems
to be getting /chosen/stdout and calls exit if it returns nothing. So I'll
need this at least for linux. (I think MorphOS may also query it to print
a banner or some messages but not sure it needs it, at least it does not
abort right away if not found.)
but to see Linux output do I need a stdout in VOF or it will just open
the serial with its own driver and use that?
So I'm not sure what's the stdout parts in the current vof patch does
and if I need that for anything. I'll try to experiment with it some
more but fixing the ld and Kconfig seems to be enough to get it work for
me.
So for the client to print something, /chosen/stdout needs to have a
valid ihandle.
The only way to get a valid ihandle is having a valid phandle which
vof_client_open() can open.
A valid phandle is a phandle of any node in the device tree. On spapr we
pick some spapr-vty, open it and store in /chosen/stdout.
From this point output from the client can be seen via a tracepoint.
I've got it now. Looking at the original firmware device tree dump:
https://osdn.net/projects/qmiga/wiki/SubprojectPegasos2/attach/PegasosII_OFW-Dump.txt
I see that /chosen/stdout points to "screen" which is an alias to
/bootconsole. Just adding an empty /bootconsole node in the device tree and
vof_client_open_store() that as /chosen/stdout works and I get output via
vof_write traces so this is enough for now to test Linux. Properly
connecting a serial backend can thus be postponed.
So with this the Linux kernel does not abort on the first device tree
access but starts to decompress itself then the embedded initrd and crashes
at calling setprop:
[...]
vof_client_handle: setprop
Thread 4 "qemu-system-ppc" received signal SIGSEGV, Segmentation fault.
(gdb) bt
#0 0x0000000000000000 in ()
#1 0x0000555555a5c2bf in vof_setprop
(vof=0x7ffff48e9420, vallen=4, valaddr=<optimized out>,
pname=<optimized out>, nodeph=8, fdt=0x7fff8aaff010, ms=0x5555564f8800)
at ../hw/ppc/vof.c:308
#2 0x0000555555a5c2bf in vof_client_handle
(nrets=1, rets=0x7ffff48e93f0, nargs=4, args=0x7ffff48e93c0,
service=0x7ffff48e9460 "setprop",
vof=0x7ffff48e9420, fdt=0x7fff8aaff010, ms=0x5555564f8800) at
../hw/ppc/vof.c:842
#3 0x0000555555a5c2bf in vof_client_call
(ms=0x5555564f8800, vof=vof@entry=0x55555662a3d0,
fdt=fdt@entry=0x7fff8aaff010, args_real=args_real@entry=23580472)
at ../hw/ppc/vof.c:935
loooks like it's trying to set /chosen/linux,initrd-start: