CVS commit: src/sys/arch/powerpc/oea

["Jason R Thorpe" <thorpej%netbsd.org@localhost>]

Module Name:    src
Committed By:   thorpej
Date:           Wed Feb 24 16:53:00 UTC 2021

Modified Files:
        src/sys/arch/powerpc/oea: ofw_subr.S ofwoea_machdep.c

Log Message:
Don't save the firmware's copy of SPRG[0-3], and don't fiddle with
SPRG[0-3] in the firmware trampoline.  Section 7.1 of the OpenFirmware
PowerPC CPU bindings says that firmware "client interface shall not modify"
when in virtual-mode, and "client interface shall preserve" in real-mode.

This is important because in vritual-mode, DSI exceptions will land in
the kernel's DSI exception handler, and that handler depends on the
kernel's SPRG0 value (it contains the pointer to the cpu_info for that
CPU).

Additionally, in the firmware trampoline, point curcpu at an empty
ofw_battable.  This ensures that the DSI exception handler won't
load a BAT register with a kernel block translation that clobbers
a segment translation owned by the firmware.  Eventually, this ofw_battable
might contain some of the larger translations owned by the firmware.


To generate a diff of this commit:
cvs rdiff -u -r1.17 -r1.18 src/sys/arch/powerpc/oea/ofw_subr.S
cvs rdiff -u -r1.53 -r1.54 src/sys/arch/powerpc/oea/ofwoea_machdep.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.