RTEMS CPU Architecture Supplement
As discussed above, the ARM's call and return mechanism dos
not automatically save any registers. RTEMS uses the registers
r0, r1, r2, and r3 as scratch registers and
per ARM calling convention, the lr register is altered
as well. These registers are not preserved by RTEMS directives
therefore, the contents of these registers should not be assumed
upon return from any RTEMS directive.
RTEMS CPU Architecture Supplement
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