Re: Regression in 4.11 - PowerPC crashes on boot, bisected to commit 5657933dbb6e

[Bart Van Assche]

On Thu, 2017-03-02 at 16:14 +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2017-03-01 at 21:26 -0600, Larry Finger wrote:
> > My Powerbook G4 Aluminum generates a fatal splat early in the boot process, just 
> > after identifying the driver for the disk. Unfortunately, it turns off almost 
> > immediately, thus I cannot report the message. After this bug has been 
> > triggered, the system clock has been reset to Dec. 31, 1969. I assume this is a 
> > side effect of an uncontrolled DMA operation.
> > 
> > This problem has been bisected to commit 5657933dbb6e ("treewide: Move dma_ops 
> > from struct dev_archdata into struct device").
> 
> Side effect of a crash during boot... the PMU gets upset when we crash while
> there's a request in flight, that's probably what is happening.
> 
> As to why that commit is broken, I don't have time to look into it right  now,
> maybe next week of nobody beats me to it.

The results of my attempts so far to create a PPC VM:
* I have not found a CPU / architecture / CD bus type / combination for which the
  Gentoo installation CD was able to recognize the boot medium
  (http://distfiles.gentoo.org/releases/ppc/autobuilds/20140713/install-powerpc-minimal-20140713.iso).
* Same problem with the openSUSE Leap CD: apparently that software does not recognize
  the qemu SCSI CD
  (http://mirror.datto.com/opensuse/ports/ppc/distribution/leap/42.2/iso/openSUSE-Leap-42.2-NET-ppc64le-Build0156-Media.iso).
* openSUSE Tumbleweed recognizes the qemu SCSI CD. After it has loaded the installation
  software however it displays an message reporting that an error occurred during
  installation and displays a menu. Making a selection from that menu is not possible
  because the only key from the keyboard it recognizes is "Enter"
  (http://mirror.datto.com/opensuse/ports/ppc/tumbleweed/iso/openSUSE-Tumbleweed-DVD-ppc64-Snapshot20170303-Media.iso).

Does anyone have a suggestion for how to proceed?

Thanks,

Bart.