hi,
somebody please help me understanding the following code. since
this code is referenced from setup.c how does the compiler put in
the physical address of the machine descriptor in r5 ? also this address
i dont understand why it is metioned as physical !!!
/*
* Lookup machine architecture in the linker-build list of
architectures.
* Note that we can't use the absolute addresses for the __arch_info
* lists since we aren't running with the MMU on (and therefore, we are
* not in the correct address space). We have to calculate the offset.
*
* r1 = machine architecture number
* Returns:
* r3, r4, r6 corrupted
* r5 = mach_info pointer in physical address space
*/
.type __lookup_machine_type, %function
__lookup_machine_type:
adr r3, 3b
ldmia r3, {r4, r5, r6}
sub r3, r3, r4 @ get offset between
virt&phys
add r5, r5, r3 @ convert virt
addresses to
add r6, r6, r3 @ physical address
space
rsb r3, r5, r6 @ number of machine
types
teq r3, #SIZEOF_MACHINE_DESC @ only one?
ldreq r1, [r5] @ if so do not bother
with r1
beq 2f @ ...and be happy.
1: ldr r3, [r5] @ get machine type
teq r3, r1 @ matches loader
number?
beq 2f @ found
add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
cmp r5, r6
blt 1b
mov r5, #0 @ unknown machine
2: mov pc, lr
TIA
regards
Srinivas Bakki
