Re: Old PowerMac G5 2-socket/2-cores-each: head -r368820 kernel reports: bus_dmamem_alloc failed to align memory properly

[Brandon Bergren]

On Mon, Dec 21, 2020, at 11:02 PM, Brandon Bergren wrote:
> 
> 
> On Mon, Dec 21, 2020, at 10:25 PM, Dennis Clarke via freebsd-ppc wrote:
> >
> > Well, I had to give it a try :
> > 
> > https://beta.genunix.com/freebsd/ppc64/power_mac_quad_freebsd_13_current_17_dec_2020_fail.png
> > 
> 
> Try the following in openfirmware before booting:
> 
> dev /memory at 0 100000 1000 do-unmap
> 
> There are certain versions of OpenFirmware that leave a page mapped 
> with the wrong protections erroneously and this smells like that bug to 
> me.

In fact, given the srr0 value in the fault, I am *certain* this is your problem.

You can use nvedit to make this bugfix permanent for a given machine (We don't have our own guide, but the NetBSD guide @ https://www.netbsd.org/ports/macppc/nvedit.html is usable to apply this patch.)

-- 
  Brandon Bergren
  bdragon at FreeBSD.org