OF: Add a separate direct kernel loading word
Currently, go-64 is used for booting a kernel from qemu (i.e. -kernel).
However, there is an expectation from users that this should be able to
boot not just vmlinux kernels but things like Zimages too.
The bootwrapper of a BE zImage is a 32-bit ELF. Attempting to load that
with go-64 means that it will be ran with MSR_SF set (64-bit mode). This
crashes early in boot (usually due to what should be 32-bit operations
being done with 64-bit registers eventually leading to an incorrect
address being generated and branched to).
Note that our 64-bit payloads are prepared to enter with MSR_SF cleared
and set it themselves very early.
Add a new word named go-direct that will execute any simple payload
in-place and will enter with MSR_SF cleared. This allows booting a BE
zImage from qemu with -machine kernel-addr=0.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
diff --git a/board-qemu/slof/OF.fs b/board-qemu/slof/OF.fs
index f0fc9c6..3bcb2af 100644
--- a/board-qemu/slof/OF.fs
+++ b/board-qemu/slof/OF.fs
@@ -303,10 +303,9 @@
: (boot-ram)
direct-ram-boot-size 0<> IF
." Booting from memory..." cr
- s" go-args 2@ " evaluate
- direct-ram-boot-base 0
+ s" direct-ram-boot-base to go-entry" evaluate
s" true state-valid ! " evaluate
- s" disable-watchdog go-64" evaluate
+ s" disable-watchdog go-direct" evaluate
THEN
;
diff --git a/slof/fs/boot.fs b/slof/fs/boot.fs
index 6d16c54..a6dfdf3 100644
--- a/slof/fs/boot.fs
+++ b/slof/fs/boot.fs
@@ -112,6 +112,12 @@
claim-list elf-release 0 to claim-list
;
+: go-direct ( -- )
+ 0 ciregs >r3 ! 0 ciregs >r4 ! 0 ciregs >r2 !
+ msr@ 7fffffffffffffff and 2000 or ciregs >srr1 !
+ go-args 2@ go-entry call-client
+;
+
: set-le ( -- )
1 ciregs >r13 !
;