PowerPC + SMP

Paul Mackerras paulus at samba.org
Wed Apr 27 09:04:48 EST 2005

Stuart Yoder writes:

> That raises a question though-- how can I know what assumptions the
> kernel makes about the state of the CPU/system when it begins execution?
> Is this clearly documented anywhere?

In general the kernel assumes that firmware has set up the HID
registers, caches, northbridge, memory controller, memory, etc., in a
suitable state for the machine to run at full speed.  There is code to
set and clear various HID bits, depending on the specific cpu model -
look for the __setup_cpu_* functions in arch/ppc/kernel/*.S.  I guess
we could add code to set ABE and SYNCBE on 7447A processors on SMP
systems; I can't imagine that any SMP system would require them to be


More information about the Linuxppc-dev mailing list