Regression in booting HelenOS/ppc under Qemu

[Jakub Jermar]

Mark Cave-Ayland identified Qemu commit 41557447d30eeb944e42069513df13585f5e6c7f as the first bad commit which prevents HelenOS/ppc from booting with OpenBIOS taken from Qemu 0.11.1. Note that we deliberately use the OpenBIOS from Qemu 0.11.1 because there is another suspected, unrelated bug in newer versions of OpenBIOS.

For reproducing purposes, the following HelenOS image can be used (latest HelenOS exhibits the same behavior):

http://www.helenos.org/releases/HelenOS-0.4.2-ppc32.iso

Commit 41557447d30eeb944e42069513df13585f5e6c7f will result in HelenOS not making any further progress after it prints "init: Spawning /srv/devfs".

The previous commit, f844c817d726cd2bdb431aa41c8217891ede2eaf, works fine - HelenOS will spawn a couple of shell instances and will be accepting user input.

[Jakub Jermar (jakub)]

How to reproduce:

1. make sure openbios-ppc from Qemu 0.11.1 is installed
2. $ qemu-system-ppc -cdrom HelenOS-0.4.2-ppc32.iso -boot d

[Artyom Tarasenko (atar4qemu)]

Just for the reference,

commit 41557447d30eeb944e42069513df13585f5e6c7f
Author: Alexander Graf <email address hidden>
Date: Fri Sep 10 15:08:34 2010 +0000

    PPC: Redesign interrupt trigger path

    According to the Book3S spec, the interrupt context starts with an MSR
    value that is rather simple. If we leave out the HV case, it's almost
    always 0.

    To reflect this, let's redesign the way that MSR value gets calculated.
    Using this, we also squash the bug where MSR_POW can slip through into
    the interrupt handler MSR.

    Reported-by: Thomas Monjalon <email address hidden>
    Signed-off-by: Alexander Graf <email address hidden>
    Signed-off-by: Edgar E. Iglesias <email address hidden>

[Mark Cave-Ayland (mark-cave-ayland)]

Just for an update: the TLB patch has been applied to ppc-next by Andreas and so should be in git master shortly:

http://lists.gnu.org/archive/html/qemu-ppc/2012-03/msg00162.html

I've also reworked the MSR flags patch based upon feedback from David/Scott and posted a revised version here, for which I'm still awaiting feedback (I suspect we need to wait for Alex to get back from holiday before we can get a final decision on this):

http://lists.gnu.org/archive/html/qemu-ppc/2012-04/msg00025.html

[agraf (agraf)]

Mark's TLB patch was enough to fix HelenOS :).

[Stewart Smith (stewart-ibm)]

Works in current qemu trunk, setting Fix Released.