Re: [Qemu-devel] [PATCH 16/32] ppc: Rework NIP updates vs. exception generation

[Benjamin Herrenschmidt]

On Wed, 2016-07-27 at 12:19 +1000, David Gibson wrote:
> twi etc will generally resume from the next instruction if they trap,
> yes?  In which case I'm a bit confused by the nip - 4.  But possibly I
> just haven't correctly followed all the nip update logic changed by
> this patch.

>From the ISA (Program Check interrupt)

Trap
A Trap type Program interrupt is generated when
any of the
conditions specified in a Trap instruction
is met.

The following registers are set:
SRR0
For all Program interrupts except a Float-
ing-Point Enabled Exception type Program
interrupt, set to the effective address of the
instruction that caused the corresponding
exception.

Cheers,
Ben.