Re: Hang with isync

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]>


On 9/20/06, Benjamin Herrenschmidt [off-list ref] wrote:

On Tue, 2006-09-19 at 18:16 -0700, Manoj Sharma wrote:

quoted

        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         2.5 onwards, I find that "sync; isync" has been replaced by a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.