Re: [regression bisected] HR-timers bug >=2.6.25

From: Justin Madru
Date: Sun May 18 2008 - 18:15:44 EST

those can be obtained by adding:


to the kernel boot parameters - it depends a bit on the hardware which
of the two choices works best, just start with 1 and if that doesn't
work try 2.

This enabled the NMI watchdog and that will print a backtrace when it
times out after 30 or so seconds.
I got netconsole to work, but it stops logging. Below are the last few lines of output:

ACPI: device:25 is registered as cooling_device2
input: Video Bus as /devices/LNXSYSTM:00/device:00/PNP0A03:00/device:21/device:22/input/input4
phy0: Selected rate control algorithm 'iwl-3945-rs'
ACPI: Video Device [VID] (multi-head: yes rom: no post: no)
ACPI: device:2a is registered as cooling_device3
input: Video Bus as /devices/LNXSYSTM:00/device:00/PNP0A03:00/device:27/input/input5
ACPI: Video Device [VID1] (multi-head: yes rom: no post: no)
input: Video Bus as /devices/LNXSYSTM:00/device:00/PNP0A03:00/device:2c/input/input6
ACPI: Video Device [VID2] (multi-head: yes rom: no post: no)
ACPI: PCI Interrupt 0000:00:1b.0[A] -> GSI 21 (level, low) -> IRQ 21
PCI: Setting latency timer of device 0000:00:1b.0 to 64
ACPI: PCI interrupt for device 0000:0b:00.0 disabled
Synaptics Touchpad, model: 1, fw: 6.2, id: 0x180b1, caps: 0xa04713/0x200000
input: SynPS/2 Synaptics TouchPad as /devices/platform/i8042/serio1/input/input7
dcdbas dcdbas: Dell Systems Management Base Driver (version 5.6.0-3.2)
fuse init (API version 7.9)
I do get several of the following after several minuets
trying to get vblank count for disabled pipe 0

Even when I got the screen to "fade" out, I never got anything more. I guess it doesn't hang the kernel. It just must be a different timing problem related to usplash/xorg which is exposed by the scheduler timing changes since around that one commit that I found by git bisect. It does seem to be a very weird problem.

Any ideas on how to help the xorg intel driver developers pinpoint the problem?


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