Disable VSX instruction

VSX bit is enabled by default for Power7 and Power8 CPU models,
so we need to disable them in order to avoid instruction exceptions.
Kernel will activate it when necessary.

* grub-core/kern/powerpc/ieee1275/startup.S: Disable VSX.

Also-By: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
Also-By: Colin Watson <cjwatson@debian.org>
Origin: other, https://lists.gnu.org/archive/html/grub-devel/2014-09/msg00078.html
Last-Update: 2015-01-27

Patch-Name: ppc64el-disable-vsx.patch

diff --git a/grub-core/kern/powerpc/ieee1275/startup.S b/grub-core/kern/powerpc/ieee1275/startup.S
index 21c884b433897e1dae15b06d1340ce0280f77c31..de9a9601a9c2742695b78a4a8844d26492092082 100644 (file)
--- a/grub-core/kern/powerpc/ieee1275/startup.S
+++ b/grub-core/kern/powerpc/ieee1275/startup.S
@@ -20,6 +20,8 @@
 #include <grub/symbol.h>
 #include <grub/offsets.h>
 
+#define MSR_VSX 0x80
+
 .extern __bss_start
 .extern _end
 
@@ -28,6 +30,16 @@
        .globl  start, _start
 start:
 _start:
+ _start:
+
+    /* Disable VSX instruction */
+       mfmsr  0
+       oris   0,0,MSR_VSX
+       /* The "VSX Available" bit is in the lower half of the MSR, so we
+          don't need mtmsrd, which in any case won't work in 32-bit mode.  */
+       mtmsr  0
+       isync
+
        li      2, 0
        li      13, 0