Re: Linux kernel 3.x problems on PowerMac G5

On Sun, 2013-03-10 at 01:26 +0100, Phileas Fogg wrote:

i managed to find the bad commit after a couple of days bisecting.

Thanks !

----------------------------
44ae3ab3358e962039c36ad4ae461ae9fb29596c is the first bad commit
commit 44ae3ab3358e962039c36ad4ae461ae9fb29596c
Author: Matt Evans [off-list ref]
Date:   Wed Apr 6 19:48:50 2011 +0000

     powerpc: Free up some CPU feature bits by moving out MMU-related 
features

     Some of the 64bit PPC CPU features are MMU-related, so this patch moves
     them to MMU_FTR_ bits.  All cpu_has_feature()-style tests are moved to
     mmu_has_feature(), and seven feature bits are freed as a result.

     Signed-off-by: Matt Evans [off-list ref]
     Signed-off-by: Benjamin Herrenschmidt [off-list ref]
--------------------------------

Have you verified that if you checkout git at the above commit point, it
fails and if you then just revert that commit on top, it works again ?

The above should have been mostly a NOP change but I'll have a closer
look in case a typo of some kind actually broke something.

Actually, there are 2 problems i found.
The first problem occurs when i enable IDE CDROM driver on my machine.
The following commit causes hangs on my machine at boot:

Ok. You may want to switch to the new libata instead of the old IDE
driver too

(CONFIG_IDE off, CONFIG_ATA on, CONFIG_PATA_MACIO on and from there it
will use the SCSI CDROM driver).

----------------------
commit 5b03a1b140e13a28ff6be1526892a9dc538ddef6
Author: Tejun Heo [off-list ref]
Date:   Wed Mar 9 19:54:27 2011 +0100

     ide: Convert to bdops->check_events()

     Convert ->media_changed() to the new ->check_events() method.  The
     conversion is mostly mechanical.  The only notable change is that
     cdrom now doesn't generate any event if @slot_nr isn't CDSL_CURRENT.
     It used to return -EINVAL which would be treated as media changed.  As
     media changer isn't supported anyway, this doesn't make any
     difference.

     This makes ide emit the standard disk events and allows kernel event
     polling.  Currently, only MEDIA_CHANGE event is implemented.  Adding
     support for EJECT_REQUEST shouldn't be difficult; however, given that
     ide driver is already deprecated, it probably is best to leave it
     alone.

     Signed-off-by: Tejun Heo [off-list ref]
----------------------------




If i disable IDE CDROM driver then the Linux kernel boots again
and then it hits the commit 44ae3ab3358e962039c36ad4ae461ae9fb29596c
and hangs again :)

The commit eca590f402332ab873d13f2d8d00fa0b91cfff36 which is before
the commit 44ae3ab3358e962039c36ad4ae461ae9fb29596c works fine,
i tested it myself to be on the safe side.

Ok thanks. I'll dig a bit if I get a chance next week.

Cheers,
Ben.

Regards