diff options
Diffstat (limited to 'arch/microblaze/kernel/head.S')
| -rw-r--r-- | arch/microblaze/kernel/head.S | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/arch/microblaze/kernel/head.S b/arch/microblaze/kernel/head.S index 0db20b5abb54..778a5ce2e4fc 100644 --- a/arch/microblaze/kernel/head.S +++ b/arch/microblaze/kernel/head.S @@ -62,15 +62,14 @@ real_start: 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. + * According to Xilinx, msrclr instruction behaves like 'mfs rX,rpc' + * if the msrclr instruction is not enabled. We use this to detect + * if the opcode is available, by issuing msrclr and then testing the result. + * r8 == 0 - msr instructions are implemented + * r8 != 0 - msr instructions are not implemented */ - /* 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 + msrclr r8, 0 /* clear nothing - just read msr for test */ + cmpu r8, r8, r1 /* r1 must contain msr reg content */ /* 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. |