Re: amd64 cdrom access locks system

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Your workaround does indeed seem to work around the problem.
I can rip tracks from a cd now and I don't get a lock up
anymore.

But the first time I do something with the CD I get this...

warning: many lost ticks.
Your time source seems to be instable or some driver is hogging interupts.
rip __do_softirq+0x48/0xb0
Falling back to HPET

From then on I'm guessing I'm using the HPET and I don't
get any more of these warnings.

I did check on DMA on for the device. I can't get it
to support DMA...

root@mail:/root# hdparm -d 1 /dev/hda

/dev/hda:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma    =  0 (off)

I don't know what else to "fiddle" with to get it working. My guess is that DMA is not currently supported at all for the chipset/motherboard
I have. (As I said before, lspci seems to indicate that a lot of stuff
on this motherboard is "unknown" hardware; would be nice to get it
"known" but I don't know how. I can only be somebody's guinea pig for
patches ;-) Or maybe I am missing some trick to enabling DMA? I have
it enabled by default in my kernel .config

Anyhow, thanks for the work around. I can at least use my burner now.
Though I suspect you want a "real" fix sometime as for why the HPET
tick obtained a 0 value.  If you want me to test another patch
towards this goal just let me know.

- Jeff

Andrew Morton wrote:
Jeff Wiegley <[email protected]> wrote:

warning: many lost ticks.
Your time source seems to be instable or some driver is hogging interupts
rip default_idle+0x24/0x30
Falling back to HPET
divide error: 0000 [1] PREEMPT
...
RIP: 0010:[<ffffffff80112704>] <ffffffff80112704>{timer_interrupt+244}


The timer code got confused, fell back to the HPET timer and then got a
divide-by-zero in timer_interrupt().  Probably because variable hpet_tick
is zero.

- It's probably a bug that the cdrom code is holding interrupts off for
  too long.

  Use hdparm and dmesg to see whether the driver is using DMA.  If it
  isn't, fiddle with it until it is.

- It's possibly a bug that we're falling back to HPET mode just because
  the cdrom driver is being transiently silly.

- It's surely a bug that hpet_tick is zero after we've switched to HPET mode.




Please test this workaround:


 arch/x86_64/kernel/time.c |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)

diff -puN arch/x86_64/kernel/time.c~x86_64-div-by-zero-fix arch/x86_64/kernel/time.c
--- 25/arch/x86_64/kernel/time.c~x86_64-div-by-zero-fix	Thu Jun  9 15:51:50 2005
+++ 25-akpm/arch/x86_64/kernel/time.c	Thu Jun  9 15:53:08 2005
@@ -75,6 +75,11 @@ unsigned long __wall_jiffies __section_w
 struct timespec __xtime __section_xtime;
 struct timezone __sys_tz __section_sys_tz;
+static inline unsigned long fixed_hpet_tick(void)
+{
+	return hpet_tick ? hpet_tick : 1;
+}
+
 static inline void rdtscll_sync(unsigned long *tsc)
 {
 #ifdef CONFIG_SMP
@@ -305,7 +310,7 @@ unsigned long long monotonic_clock(void)
} while (read_seqretry(&xtime_lock, seq));
 		offset = (this_offset - last_offset);
-		offset *=(NSEC_PER_SEC/HZ)/hpet_tick;
+		offset *=(NSEC_PER_SEC/HZ)/fixed_hpet_tick();
 		return base + offset;
 	}else{
 		do {
@@ -393,11 +398,11 @@ static irqreturn_t timer_interrupt(int i
if (vxtime.mode == VXTIME_HPET) {
 		if (offset - vxtime.last > hpet_tick) {
-			lost = (offset - vxtime.last) / hpet_tick - 1;
+			lost = (offset - vxtime.last) / fixed_hpet_tick() - 1;
 		}
- monotonic_base += - (offset - vxtime.last)*(NSEC_PER_SEC/HZ) / hpet_tick;
+		monotonic_base +=  (offset - vxtime.last)*(NSEC_PER_SEC/HZ) /
+					fixed_hpet_tick();
vxtime.last = offset;
 #ifdef CONFIG_X86_PM_TIMER
_


--
Jeff Wiegley, PhD
Cyte.Com, LLC
(ignore:cea2d3a38843531c7def1deff59114de)
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux