Re: head -r354701 seems to be why/when 32-bit powerpc FreeBSD stopped being able to boot PowerMac G5s (2 socket ones, anyw ay)

This one should now be fixed as of r356862.

On Fri, Jan 3, 2020, at 7:08 PM, Brandon Bergren wrote:
> I do have fixes for this (the offset computation was assuming 
> generictrap was always generictrap) but there are still additional 
> problems that I am trying to chase down.
> 
> I was banging my head on the bridge mode trap code for days and I still 
> haven't isolated what's going wrong with memory.
> 
> I might just clean up and submit my fixes I have so far, even though 
> they aren't sufficient to get things working fully again. I think we're 
> also hitting a clang optimization issue. :-/
> 
> On Fri, Jan 3, 2020, at 3:18 AM, Mark Millard wrote:
> > (NOTE: I only have access to 2-socket G5's, so I do not
> > know the behavior for other kinds. I've access to both
> > 2-cores-each and 1-core-each contexts.)
> > 
> > This analysis is based on installing
> > artifact.ci.freebsd.org materials and testing
> > if they boot the G5's or not. Other than
> > a little /etc/fstab and /boot/loader.conf
> > material, the artifact materials are unchanged.
> > My builds are not involved.
> > 
> > -r354702 fails to boot. (Details later, below.)
> > 
> > -r354700 (the closest prior 32-bit powerpc
> > artifcact) boots fine.
> > 
> > 
> > -r354701 and -r354702 are:
> > 
> > 
> > 
> > Author: bdragon
> > Date: Thu Nov 14 04:34:17 2019
> > New Revision: 354701
> > URL: 
> > https://svnweb.freebsd.org/changeset/base/354701
> > 
> > 
> > Log:
> >   powerpc: Kernel fixes for ppc32 and powerpcspe w/ lld
> >   
> >   Fix wrong section ordering that was causing a ".got is not contiguous with
> >   other relro sections" lld error. This also brings ldscript.powerpc and
> >   ldscript.powerpcspe closer to ldscript.powerpc64.
> >   
> >   Also, remove unnecessary text relocs from the ppc32 AIM trap code.
> > 
> > 
> > 
> > Author: mav
> > Date: Thu Nov 14 04:34:58 2019
> > New Revision: 354702
> > URL: 
> > https://svnweb.freebsd.org/changeset/base/354702
> > 
> > 
> > Log:
> >   Make ntb(4) send bus_get_dma_tag() requests to parent buses passing real
> >   bus' child pointers instead of grandchilds.
> >   
> >   DMAR does not like requests from devices not parented directly by PCI.
> > 
> > 
> > 
> > At this point I'm guessing -r354701 since it
> > is powerpc specific.
> > 
> > 
> > The following is based on typing from
> > screen images . . .
> > 
> > Failure style #1:
> > 
> > . . .
> > Trying to mount root from ufs:/dev/ada0s3 [rw,noatime]...
> > SMP: 2 CPUs found; 2 CPUs usable; 1 CPUs woken
> > WARNING: WITNESS option enabled, expect reduced performance.
> > 
> > (And that is all.)
> > 
> > Failure style #2:
> > 
> > . . .
> > Trying to mount root from ufs:/dev/ada0s3 [rw,noatime]...
> > SMP: 2 CPUs found; 2 CPUs usable; 1 CPUs woken
> > WARNING: WITNESS option enabled, expect reduced performance.
> > [ thread pid 1 tid 100002 ]
> > Stopped at dsmisssize+0x68c: illegal instruction 0
> > db> 
> > 
> > (So just 3 more lines showing up.)
> > 
> > 
> > 
> > NOTE: I do not claim that there are not more
> > problems later in head's history that fail
> > even earlier in the boot, thus hiding what is
> > reported here. There is one that I've not yet
> > isolated the first artifact version for. Thus,
> > testing for what I'm reporting here may require
> > using older vintages of FreeBSD, unless other
> > problems are dealt with first.
> > 
> > 
> > ===
> > Mark Millard
> > marklmi at yahoo.com
> > ( dsl-only.net went
> > away in early 2018-Mar)
> > 
> >
> 
> -- 
>   Brandon Bergren
>   [email protected]
>

-- 
  Brandon Bergren
Technical Generalist
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