CURRENT -r361544 breaks 2-socket PowerMac G4 booting: "powerpc/mmu: Convert PowerPC pmap drivers to ifunc from kobj"

[Mark Millard]

[Continuation of testing kernel builds, but testing my own kernel
builds for the head powerpc updates not available from artifacts.ci.
Ends up: -r361544 breaks things.]

On 2020-Dec-30, at 17:07, Mark Millard <marklmi at yahoo.com> wrote:

> A quick summary of what I found in a crude artifact bisect is coded into
> the filenames listed later. The earliest major point is the "1 CPUs woken"
> issue from what I can tell. It still happens in -r368820 .
> 
> "2cpus_booted" means things booted and worked normally.
> 
> "1cpuwoke_" means that the following was reported:
> 
> SMP: 2 CPUs found; 2 CPUs usable; 1 CPUs woken
> 
> "_hung" means that it appeared to stop without reporting a crash. Never
> got to login prompt.
> 
> "crashes_quickly" means that the the kernel did not get very far before
> the crash happened.
> 
> -rw-r--r--   1 root  wheel  19179328 May 25 21:44:01 2020 kernel-r361494-2cpus_booted.txz
> 
> Note: No artifact kernel.txz files for the range -r361495 .. -r361583 .
> powerpc checkins in that range include:
> 
> -r361542 : [PowerPC] Fix invalid asm in trap code (Brandon)
> -r361544 : powerpc/mmu: Convert PowerPC pmap drivers to ifunc from kobj (Justin)
> -r361545 : Properly sort ifdef archs in vm_fault_soft_fast superpage guards. (Justin)
> -r361568 : [PowerPC] Fix radix crash when passing -1 from userspace (Brandon)
> -r361570 : powerpc/pmap: Remove some debug from r361544 (Justin)
> 
> -rw-r--r--   1 root  wheel  19133836 May 28 04:28:01 2020 kernel-r361584-1cpuwoke_hung.txz
> -rw-r--r--   1 root  wheel  19181596 May 29 04:42:42 2020 kernel-r361624-1cpuwoke_hung.txz
> -rw-r--r--   1 root  wheel  19254832 Jun  3 10:26:42 2020 kernel-r361754-1cpuwoke_hung.txz
> -rw-r--r--   1 root  wheel  18869112 Jun 10 16:53:57 2020 kernel-r362034-1cpuwoke_hung.txz
> -rw-r--r--   1 root  wheel  19245524 Jul  8 06:04:41 2020 kernel-r363008-1cpuwoke_hung.txz
> -rw-r--r--   1 root  wheel  19259816 Aug 16 12:03:55 2020 kernel-r364274-1cpuwoke_hung.txz
> 
> NOTE: -r364284 is where clang 11 started and the -O newly meaning -O1 problem started.
>      (Previously -O meant -O2. -O1 messed up the kernel's ifunc handling until it
>      was changed to explicitly use -O2.)
> 
> -rw-r--r--   1 root  wheel  19369960 Aug 22 11:38:22 2020 kernel-r364488-crashes_quickly.txz
> -rw-r--r--   1 root  wheel  19203632 Sep  1 01:38:18 2020 kernel-r365024-crashes_quickly.txz
> -rw-r--r--   1 root  wheel  19367776 Sep  3 11:02:58 2020 kernel-r365304-crashes_quickly.txz
> -rw-r--r--   1 root  wheel  19279564 Sep  6 08:06:11 2020 kernel-r365378-crashes_quickly.txz
> -rw-r--r--   1 root  wheel  19205456 Sep  7 22:53:14 2020 kernel-r365444-1cpuwoke_crashes_late.txz
> -rw-r--r--   1 root  wheel  19446448 Sep 10 08:08:23 2020 kernel-r365578-1cpuwoke_hung.txz
> -rw-r--r--   1 root  wheel  19398268 Oct  9 06:05:48 2020 kernel-r366598-1cpuwoke_hung.txz
> 
> Note: -r368820 still has "1cpuwoke" status and its USB is messed up (and
>      it reports DMA misalignment) but it does boot. (I accessed it via ssh.)

Note: for the below kernel builds I provided a "int yydebug;" for:

usr.bin/localedef/localedef.c

so kernel-toolchain could build (avoiding a link failure).

Other than that, the kernel builds are of pure code from git using KERNCONF=GENERIC ,
TARGET=powerpc , TARGET_ARCH=powerpc and no other tailoring, avoiding any questions
about my personal patches contributing.


-r361542 (64cc3b0c28b9) : [PowerPC] Fix invalid asm in trap code (Brandon)

Things booted and worked as expected.


-r361544 (45b69dd63e84) : powerpc/mmu: Convert PowerPC pmap drivers to ifunc from kobj (Justin)

SMP: 2 CPUs found; 2 CPUs usable; 1 CPUs woken

was reported and it appeared to stop without reporting a crash. Never
got to login prompt.


NOTE: -r361453 was on stable/ instead of head/ so the above is a
works-then-fails pair with nothing between on CURRENT.


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)