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Message
From: Balint Cristian<cristian.balint@o...>
Date: Wed Jun 29 14:14:44 CEST 2005
Subject: [openrisc] Oops when booting Linux
On Wednesday 29 June 2005 14:46, Robert Millan wrote:
Only if you buy an FPGA board.
To be onest is not so expensive.
>
> Hi!
>
> I got an Oops when booting Linux in or1ksim. I was using linux-2.4 from CVS,
> compiled with gcc 3.4.2, running on or1ksim from HEAD branch.
>
> Boot log in uart0.tx attached, simulator log (run with verbose = 1 and
> debug = 1) attached too. I haven't used a higher debug level because lots of
> errors were printed already and most of them didn't look critical.
>
> Linux boot log lists 0xc000b898 as the PC value when exception happens. Here's
> a dasm output of this address:
>
> /usr/src/or1k/linux/linux-2.4/include/linux/list.h:83
> c000b898: d4 04 18 00 l.sw 0x0(r4),r3
>
> Corresponding C code in list.h:
>
> static inline void __list_del(struct list_head *prev, struct list_head *next)
> {
> next->prev = prev;
> prev->next = next; /* line 83 */
> }
>
> Linux boot log lists 0xc000b63c as a "Call Trace" address. Since this address
> is in the stack trace, I guess it means this is the function that called
> __list_del (please correct me if i'm confused). The info for 0xc000b63c is:
>
> /usr/src/or1k/linux/linux-2.4/kernel/sched.c:578
> c000b63c: 84 61 00 2c l.lwz r3,0x2c(r1)
> c000b640: 84 83 00 28 l.lwz r4,0x28(r3)
> c000b644: bc 24 00 02 l.sfnei r4,0x2
> c000b648: 0c 00 00 c1 l.bnf c000b94c <_schedule+0x390>
> c000b64c: 15 00 00 00 l.nop 0x0
>
> Corresponding C code in kernel/sched.c:
>
> /* move an exhausted RR process to be last.. */
> if (unlikely(prev->policy == SCHED_RR)) /* line 578 */
> if (!prev->counter) {
> prev->counter = NICE_TO_TICKS(prev->nice);
> move_last_runqueue(prev);
> }
>
> Which once preprocessed reads:
>
> if (__builtin_expect ((prev->policy == 2), 0))
> if (!prev->counter) {
> prev->counter = (((20 - (prev->nice)) >> 2) + 1);
> move_last_runqueue (prev);
> }
>
> (and I don't quite understand this, since both "unlikely" and
> "__builtin_expect" seem to be macros:
>
> ./include/linux/compiler.h:#define __builtin_expect(x, expected_value) (x)
> ./include/linux/compiler.h:#define likely(x) __builtin_expect((x),1)
> ./include/linux/compiler.h:#define unlikely(x) __builtin_expect((x),0)
> )
>
> Please let me know if you need more info. I can send you a log with higher
> debug value, or even the vmlinux file.
>
--
Cristian Balint
Romania Data Systems SA - filiala Oradea
Departamentul Tehnic
➧ str. Independentei nr. 24, Oradea
tel. + 40-259-447.252
fax. + 40-259-467.440
➧ email: cristian.balint@o...
suport@r...
➧ http://www.rdsnet.ro
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