diff options
| author | Michal Simek <monstr@monstr.eu> | 2009-08-31 16:24:56 +0200 |
|---|---|---|
| committer | Michal Simek <monstr@monstr.eu> | 2009-09-21 14:29:21 +0200 |
| commit | 9002062ff52696888847224a778a3279bc8c1cb5 (patch) | |
| tree | 8a68281f621df2702b58d38f7e13b8639db13af0 | |
| parent | 2622434ee0108c65808a63f067e72d0bbc75b372 (diff) | |
microblaze: Improve checking mechanism for MSR instruction
It is more safe to use clear instead of msrset.
We save some instructions too.
Signed-off-by: Michal Simek <monstr@monstr.eu>
| -rw-r--r-- | arch/microblaze/kernel/head.S | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/arch/microblaze/kernel/head.S b/arch/microblaze/kernel/head.S index bfc7ea801cc..697ce3007f3 100644 --- a/arch/microblaze/kernel/head.S +++ b/arch/microblaze/kernel/head.S @@ -54,19 +54,16 @@ ENTRY(_start) mfs r1, rmsr andi r1, r1, ~2 mts rmsr, r1 - /* * Here is checking mechanism which check if Microblaze has msr instructions * We load msr and compare it with previous r1 value - if is the same, * msr instructions works if not - cpu don't have them. */ - or r8, r0, r0 /* 0 - I have msr instr, 1 - I don't have */ - or r12, r0, r0 - msrset r12, 0 /* set nothing - just read msr for test */ - cmpu r12, r12, r1 - beqi r12, 1f - ori r8, r0, 1 /* I don't have msr */ -1: + /* r8=0 - I have msr instr, 1 - I don't have them */ + rsubi r0, r0, 1 /* set the carry bit */ + msrclr r0, 0x4 /* try to clear it */ + /* read the carry bit, r8 will be '0' if msrclr exists */ + addik r8, r0, 0 /* r7 may point to an FDT, or there may be one linked in. if it's in r7, we've got to save it away ASAP. |