Re: Hang with isync

On Wed, 2006-09-20 at 15:31 -0700, Manoj Sharma wrote:

This is the stack trace.

Registers:
GPR00: 00069030 C01F3000 C01F1080 00000000 00048000 C0639F48 C01F1080
FFFFFC18
GPR08: C02203FC 00000020 C0638000 C01F31B0 42FEE022 1056A7F8 00FE502A
00000000
GPR16: 00000000 FFC44232 00000000 00000000 FFC441EC 00080000 00010000
0000000A 
GPR24: 00000000 0007CD80 00000CE0 00000000 00000000 C02B0000 00000000
C02B0000

NIP; c0005da4 _<_nmask_and_or_msr+0x18/0x20 [kernel]>
Trace; c0025328 _<check_pgt_cache+0x20/0x30 [kernel]>
Trace; c0004f4c _<idled+0x58/0x70 [kernel]> 
Trace; c0004f74 _<cpu_idle+0x10/0x24 [kernel]>
Trace; c00012b0 _<rest_init+0x30/0x40 [kernel]>
Trace; c02a45a4 _<start_kernel+0x168/0x17c [kernel]>
Trace; c0000250 _<skpinv+0x1f8/0x234 [kernel]> 

Is this upstream 2.6.20 or do you have any additional patches ? (Like
Montavista stuff or RT linux or whatever ?)

It's unclear to me from just that backtrace what mask it is... it could
just be re-enabling interrupt and you have a stale IRQ line asserted....

Have you also checked the errata list for your 405 core, in case it has
a known issue ?

Ben.

On 9/20/06, Benjamin Herrenschmidt [off-list ref] wrote:
        On Tue, 2006-09-19 at 18:16 -0700, Manoj Sharma wrote:
        >         Hi,
        >
        >         We use linux kernel 2.4.20 on ppc405 and the system
        hangs once
        >         in a while when isync gets called in this function: 
        >
        >         _GLOBAL(_nmask_and_or_msr)
        >             mfmsr   r0      /* Get current msr */
        >             andc    r0,r0,r3    /* And off the bits set in
        r3 (first
        >         parm) */`
        >             or  r0,r0,r4    /* Or on the bits in r4 (second
        parm) */ 
        >             sync            /* Some chip revs have problems
        here... */
        >             isync
        >             mtmsr   r0      /* Update machine state */
        >             isync
        >             blr         /* Done */ 
        >
        >          2.5 onwards, I find that "sync; isync" has been
        replaced by a
        >         macro SYNC (defined only for 601). I don't find it
        in any
        >         changelog and reason for the change. 
        >
        >         Can someone give some information on this change?
        
        Regardless of the change... on 2.4, _nmask_and_or_msr() was
        used for a
        number of things. We would need to know where it was called
        from with 
        what values as arguments to have an idea of what's going
        wrong. It's
        probably not dying on the isync, but rather on the following
        mtmsr due
        to a problem with the values passed in....
        
        Ben.