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Revision 4a9590f3

ID4a9590f32e5692114aaae4ca10da89dac633e164

Added by Alexander Graf about 12 years ago

Make cpu_get_real_ticks use mfspr

PowerPC CPUs have had two ways to read the time base for quite some time now.
They provide it using the mfspr instruction or - if a special bit is set in
that opcode - using mftb. For timekeeping we're currently using mftb.

While trying to get Qemu up and running on an e500v2 system, I stumbled over
the CPU not supporting mftbu. It just throws an illegal instruction trap.

So let's read the SPR values instead. All PPC CPUs should support them anyways.

I tested this patch on an e500v2 system where it makes qemu work and on my 970MP
system with 32-bit user space where everything still works with this patch
applied.

Signed-off-by: Alexander Graf <>
Signed-off-by: malc <>

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