xen/arm32: head: Don't set r12 and update the documentation

Since commit 54c4ae18d158 ("xen/arm32: head: Rework and document
launch()"), the boot code is setting r12 but not read it.

So remove the two instructions setting r12 and update the documentation
to show r12 has no specific purpose.

Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Michal Orzel <michal.orzel@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
index 13cfc837d39c0241bc8c7664a55b25b532b305d8..7a906167efca8790db0b58c6aaec7a77af92242a 100644 (file)
--- a/xen/arch/arm/arm32/head.S
+++ b/xen/arch/arm/arm32/head.S
@@ -79,7 +79,7 @@
  *   r9  - paddr(start)
  *   r10 - phys offset
  *   r11 - UART address
- *   r12 - is_secondary_cpu
+ *   r12 -
  *   r13 - SP
  *   r14 - LR
  *   r15 - PC
@@ -166,8 +166,6 @@ past_zImage:
 #endif
         PRINT("- Boot CPU booting -\r\n")
 
-        mov   r12, #0                /* r12 := is_secondary_cpu */
-
         bl    check_cpu_mode
         bl    cpu_init
         bl    create_page_tables
@@ -206,8 +204,6 @@ GLOBAL(init_secondary)
         adr   r9, start              /* r9  := paddr (start) */
         sub   r10, r9, r0            /* r10 := phys-offset */
 
-        mov   r12, #1                /* r12 := is_secondary_cpu */
-
         mrc   CP32(r1, MPIDR)
         bic   r7, r1, #(~MPIDR_HWID_MASK) /* Mask out flags to get CPU ID */