diff options
authorMatthew Fortune <matthew.fortune@imgtec.com>2015-06-19 11:08:41 +0100
committerLeon Alrae <leon.alrae@imgtec.com>2015-06-26 09:08:50 +0100
commitd6ca4277eee98b3c561e21ac105199891d346d79 (patch)
parent9f6f7ca1490563d98003149e6de32caf25c670da (diff)
hw/mips: Do not clear BEV for MIPS malta kernel load
The BEV flag controls whether the boot exception vector is still in place when starting a kernel. When cleared the exception vector at EBASE (or hard coded address of 0x80000000) is used instead. The early stages of the linux kernel would benefit from BEV still being set to ensure any faults get handled by the boot rom exception handlers. This is a moot point for system qemu as there aren't really any BEV handlers, but there are other good reasons to change this... The UHI (semi-hosting interface) defines special behaviours depending on whether an application starts in an environment with BEV set or cleared. When BEV is set then UHI assumes that a bootloader is relatively dumb and has no advanced exception handling logic. However, when BEV is cleared then UHI assumes that the bootloader has the ability to handle UHI exceptions with its exception handlers and will unwind and forward UHI SYSCALL exceptions to the exception vector that was installed prior to running the application. Signed-off-by: Matthew Fortune <matthew.fortune@imgtec.com> Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
1 files changed, 1 insertions, 1 deletions
diff --git a/hw/mips/mips_malta.c b/hw/mips/mips_malta.c
index 786a8f0638..a5d64d5030 100644
--- a/hw/mips/mips_malta.c
+++ b/hw/mips/mips_malta.c
@@ -887,7 +887,7 @@ static void main_cpu_reset(void *opaque)
read only location. The kernel location and the arguments table
location does not change. */
if (loaderparams.kernel_filename) {
- env->CP0_Status &= ~((1 << CP0St_BEV) | (1 << CP0St_ERL));
+ env->CP0_Status &= ~(1 << CP0St_ERL);