[Qemu-devel] [PULL 1/2] hw/mips_malta: Fix YAMON API print routine

[Leon Alrae <leon.alrae@imgtec.com>]

From: Paul Burton <paul.burton@imgtec.com>

The print routine provided as part of the in-built bootloader had a bug
in that it attempted to use a jump instruction as part of a loop, but
the target has its upper bits zeroed leading to control flow
transferring to 0xb0000814 rather than the intended 0xbfc00814. Fix this
by using a branch instruction instead, which seems more fit for purpose.

A simple way to test this is to build a Linux kernel with EVA enabled &
attempt to boot it in QEMU. It will attempt to print a message
indicating the configuration mismatch but QEMU would previously
incorrectly jump & wind up printing a continuous stream of the letter E.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Leon Alrae <leon.alrae@imgtec.com>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
---
 hw/mips/mips_malta.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/mips/mips_malta.c b/hw/mips/mips_malta.c
index 34d41ef..e90857e 100644
--- a/hw/mips/mips_malta.c
+++ b/hw/mips/mips_malta.c
@@ -727,7 +727,7 @@ static void write_bootloader(uint8_t *base, int64_t run_addr,
     stl_p(p++, 0x00000000);                                     /* nop */
     stl_p(p++, 0x0ff0021c);                                     /* jal 870 */
     stl_p(p++, 0x00000000);                                     /* nop */
-    stl_p(p++, 0x08000205);                                     /* j 814 */
+    stl_p(p++, 0x1000fff9);                                     /* b 814 */
     stl_p(p++, 0x00000000);                                     /* nop */
     stl_p(p++, 0x01a00009);                                     /* jalr t5 */
     stl_p(p++, 0x01602021);                                     /* move a0,t3 */
-- 
2.7.4