ARM Initialization Question

Sebastian Huber sebastian.huber at
Fri Sep 12 15:16:39 UTC 2008

I am quite new to the ARM architecture and try to develop a BSP for the 
LPC2478.  I have a question to the initialization code (random start.S):

/* Set up the SVC stack pointer last and stay in SVC mode */
mov     r0, #(PSR_MODE_SVC | PSR_I | PSR_F)     /* No interrupts */
msr     cpsr, r0
ldr     r1, =_svc_stack_size
ldr     sp, =_svc_stack
add     sp, sp, r1
sub     sp, sp, #0x64

Why is 0x64 subtracted from the stack pointer?

Sebastian Huber, Embedded Brains GmbH

Address : Obere Lagerstr. 30, D-82178 Puchheim, Germany
Phone   : +49 89 18 90 80 79-6
Fax     : +49 89 18 90 80 79-9
E-Mail  : sebastian.huber at
PGP     : Public key available on request

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.

More information about the users mailing list