port-macppc/50018: macppc 7.0_RC1 ofwboot fails to load kernel on OF2 machine

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

>Number:         50018
>Category:       port-macppc
>Synopsis:       macppc 7.0_RC1 ofwboot fails to load kernel
>Confidential:   no
>Severity:       critical
>Priority:       low
>Responsible:    port-macppc-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jul 01 15:25:01 +0000 2015
>Originator:     Izumi Tsutsui
>Release:        NetBSD 7.0_RC1
>Organization:
>Environment:
System: NetBSD macppc 7.0_RC1
Architecture: powerpc
Machine: macppc
>Description:
ofwboot in NetBSD/macppc 7.0_RC1 fails to load kernel on UMAX Apus2000/200
with OpenFirmware 2.0

Boot from ATA disk:
---
Open Firmware, 2.0
To continue booting the MacOS type:
BYE<return>
To continue booting from the default boot device type:
BOOT<return>
 ok
0 > boot 
OF_open bootpath=ata/ATA-Disk@0
read stage 2 blocks: 01234. done!
starting stage 2...

>> NetBSD/macppc OpenFirmware Boot, Revision 1.12
Cannot use bootpath
Using boot-device instead
DEFAULT CATCH!, code=FFF00300 at   %SRR0: 00E01F2C   %SRR1: 00003070 
 ok
0 > 
---

"Using boot-device instead" message is here:
 http://nxr.netbsd.org/xref/src/sys/arch/macppc/stand/ofwboot/boot.c?r=1.27#260
so it fails during parsing args or loading a kernel.

Boot 7.0_RC1 ISO from SCSI CD-ROM:
---
Open Firmware, 2.0
To continue booting the MacOS type:
BYE<return>
To continue booting from the default boot device type:
BOOT<return>
 ok
0 > boot scsi/sd@3:0 
OF_open bootpath=scsi/sd@3
read stage 2 blocks: 0. done!
starting stage 2...

>> NetBSD/macppc OpenFirmware Boot, Revision 1.12
DEFAULT CATCH!, code=FFF00300 at   %SRR0: 00E01F34   %SRR1: 00003070 
 ok
0 > 
---

ofwboot taken from NetBSD/macppc 6.1.5 works properly,
even with 7.0_RC1 primary /usr/mdec/bootxx.

>How-To-Repeat:
Install NetBSD/macppc 7.0_RC1 on OF2 machine and boot it.

>Fix:
Not investigated yet.  gcc 4.8.x issue?