Public bug reported: Binary package hint: linux-image-2.6.26-5-generic
The kernel that is going into Ubuntu 8.10 has a bug that (as far as I know hasn't been fixed in upstream 2.6.26). The problem is that when using a 2.6.25 or 2.6.26 kernel the screen blanks out when entering graphical mode after the boot splash (screen never comes back on). Also sometimes the computer will completely lock up in the middle of the boot splash. This problem is known to occur when using a Intel graphics card, the problem could effect other cards too (I haven't tested). I've reported the bug (https://bugs.freedesktop.org/show_bug.cgi?id=15602) and have even found both the commit that introduced the bug (around 2.6.25-rc0) and the commit that fixes the bug (around 2.6.27-rc0). I would suggest that the commit that fixed the bug which is in 2.6.27 be backported to the 2.6.26 kernel that will go into 8.10. I've tested the 2.6.26 Ubuntu kernel and can verify that it does still has the bug. ----------------------------------------- This commit introduced the bug ----------------------------------------- commit 8f4d37ec073c17e2d4aa8851df5837d798606d6f Author: Peter Zijlstra <[EMAIL PROTECTED]> Date: Fri Jan 25 21:08:29 2008 +0100 sched: high-res preemption tick Use HR-timers (when available) to deliver an accurate preemption tick. The regular scheduler tick that runs at 1/HZ can be too coarse when nice level are used. The fairness system will still keep the cpu utilisation 'fair' by then delaying the task that got an excessive amount of CPU time but try to minimize this by delivering preemption points spot-on. The average frequency of this extra interrupt is sched_latency / nr_latency. Which need not be higher than 1/HZ, its just that the distribution within the sched_latency period is important. Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]> Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]> :040000 040000 ab225228500f7a19d5ad20ca12ca3fc8ff5f5ad1 f1742e1d225a72aecea9d6961ed989b5943d31d8 M arch :040000 040000 25d85e4ef7a71b0cc76801a2526ebeb4dce180fe ae61510186b4fad708ef0211ac169decba16d4e5 M include :040000 040000 9247cec7dd506c648ac027c17e5a07145aa41b26 950832cc1dc4d30923f593ecec883a06b45d62e9 M kernel --------------------------------- This commit fixed the bug --------------------------------- commit 31656519e132f6612584815f128c83976a9aaaef Author: Peter Zijlstra <[EMAIL PROTECTED]> Date: Fri Jul 18 18:01:23 2008 +0200 sched, x86: clean up hrtick implementation random uvesafb failures were reported against Gentoo: http://bugs.gentoo.org/show_bug.cgi?id=222799 and Mihai Moldovan bisected it back to: > 8f4d37ec073c17e2d4aa8851df5837d798606d6f is first bad commit > commit 8f4d37ec073c17e2d4aa8851df5837d798606d6f > Author: Peter Zijlstra <[EMAIL PROTECTED]> > Date: Fri Jan 25 21:08:29 2008 +0100 > > sched: high-res preemption tick Linus suspected it to be hrtick + vm86 interaction and observed: > Btw, Peter, Ingo: I think that commit is doing bad things. They aren't > _incorrect_ per se, but they are definitely bad. > > Why? > > Using random _TIF_WORK_MASK flags is really impolite for doing > "scheduling" work. There's a reason that arch/x86/kernel/entry_32.S > special-cases the _TIF_NEED_RESCHED flag: we don't want to exit out of > vm86 mode unnecessarily. > > See the "work_notifysig_v86" label, and how it does that > "save_v86_state()" thing etc etc. Right, I never liked having to fiddle with those TIF flags. Initially I needed it because the hrtimer base lock could not nest in the rq lock. That however is fixed these days. Currently the only reason left to fiddle with the TIF flags is remote wakeups. We cannot program a remote cpu's hrtimer. I've been thinking about using the new and improved IPI function call stuff to implement hrtimer_start_on(). However that does require that smp_call_function_single(.wait=0) works from interrupt context - /me looks at the latest series from Jens - Yes that does seem to be supported, good. Here's a stab at cleaning this stuff up ... Mihai reported test success as well. Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]> Tested-by: Mihai Moldovan <[EMAIL PROTECTED]> Cc: Michal Januszewski <[EMAIL PROTECTED]> Cc: Antonino Daplas <[EMAIL PROTECTED]> Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]> :040000 040000 5ae152350652713c58bd1700ba2c776a556b6985 40d22771987dc5814a1e18aa3cee82ae9e4faea5 M arch :040000 040000 4dfe3c6abd244d2da57b7801e47f073899124376 3863e3311a21dc049d5ad98f45c272e4a5269a2b M include :040000 040000 236b2824be1c7cf3c899a090498e4151543bba31 9f9779c89b781d8fa8950468deee42f419339bd7 M kernel ** Affects: linux (Ubuntu) Importance: Undecided Status: New -- Blank screen when using usplash and kernel >= 2.6.25 https://bugs.launchpad.net/bugs/258381 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
