[OpenBIOS] More work on Solaris 8 SPARC32 crash

[Mark Cave-Ayland]

On 13/02/11 14:31, Mark Cave-Ayland wrote:

> My current feeling is that maybe OpenBIOS isn't doing something right
> with PIL state somewhere, or we're reading back a zero value from either
> the clock (or a missing OpenBIOS property) which is causing us to die in
> the division in cbe_enable(). And another thing, what does cbe actually
> stand for?

Finally I finally have made some progress! :)  Firstly here is the gdb 
session with OpenBIOS from SVN trunk at the point where we hit the 
division by zero:


build at zeno:~/src/openbios/openbios-git/openbios-devel$ sparc64-linux-gdb
GNU gdb 6.8
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "--host=x86_64-unknown-linux-gnu 
--target=sparc64-linux".
(gdb) target remote :1234
Remote debugging using :1234
[New Thread 1]
0x00000000 in ?? ()
(gdb) file ../../ss5
A program is being debugged already.
Are you sure you want to change the file? (y or n) y
Reading symbols from /home/build/src/openbios/ss5...(no debugging 
symbols found)...done.
(gdb) break *0xf00a3f2c
Breakpoint 1 at 0xf00a3f2c
(gdb) cont
Continuing.

Breakpoint 1, 0xf00a3f2c in ?? ()
(gdb) stepi
0xf00a3f30 in ?? ()
(gdb)
0xf0062cf0 in __div64 ()
(gdb)
0xf0062cf4 in __div64 ()
(gdb)
0xf0062cf8 in __div64 ()
(gdb) info regi i0
i0             0x0      0
(gdb) info regi i1
i1             0x3e60c  255500
(gdb) info regi i2
i2             0x0      0
(gdb) info regi i3
i3             0x0      0
(gdb)


Browsing around the Linux source code, I saw some comments mentioning 
that the level 14 timer was handled by OBP, so I made the following 
experimental change in drivers/obio.c:

     counter_regs->cpu_timers[0].l14_timer_limit = 0x55555555;

And now I don't get the divide by zero error any more:

build at zeno:~/src/openbios/openbios-git/openbios-devel$ sparc64-linux-gdb
GNU gdb 6.8
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "--host=x86_64-unknown-linux-gnu 
--target=sparc64-linux".
(gdb) target remote :1234
Remote debugging using :1234
[New Thread 1]
0x00000000 in ?? ()
(gdb) file ../../ss5
A program is being debugged already.
Are you sure you want to change the file? (y or n) y
Reading symbols from /home/build/src/openbios/ss5...(no debugging 
symbols found)...done.
(gdb) break *0xf00a3f2c
Breakpoint 1 at 0xf00a3f2c
(gdb) cont
Continuing.

Breakpoint 1, 0xf00a3f2c in ?? ()
(gdb) stepi
0xf00a3f30 in ?? ()
(gdb)
0xf0062cf0 in __div64 ()
(gdb)
0xf0062cf4 in __div64 ()
(gdb)
0xf0062cf8 in __div64 ()
(gdb) info regi i0
i0             0x0      0
(gdb) info regi i1
i1             0x7a6fc  501500
(gdb) info regi i2
i2             0x0      0
(gdb) info regi i3
i3             0x53555408       1398101000
(gdb)


However I still don't get much further with the boot because I now get 
stuck in another loop which keeps outputting the following onto the QEMU 
console:

spurious interrupt at processor level 10
spurious interrupt at processor level 10
spurious interrupt at processor level 10
...etc...

So my next question is that if OpenBIOS is supposed to handle the level 
14 timer, what should it doing with it? And is there a relationship 
between the level 14 timer and level 10 timer which causes one to 
trigger the other?


ATB,

Mark.

-- 
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
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