Peter Maydell <peter.mayd...@linaro.org> writes:
> On Tue, 12 Apr 2022 at 11:45, Alex Bennée <alex.ben...@linaro.org> wrote: >> >> When accessing HW via the gdbstub we can't easily figure out what the >> cpu_index is. The canonical case is current_cpu but for some cases >> that will be NULL. For debug accesses we can overload requester_id and >> make the GIC a bit smarter about fishing that out. >> >> [AJB: very much a PoC hack for now but interested if this makes sense. >> We could encode cpu_index in another field but that would grow >> MxTxAttrs even more.] >> >> Signed-off-by: Alex Bennée <alex.ben...@linaro.org> >> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/124 >> --- >> include/exec/memattrs.h | 2 +- >> hw/core/cpu-sysemu.c | 15 +++++++++++---- >> hw/intc/arm_gic.c | 33 +++++++++++++++++++-------------- >> 3 files changed, 31 insertions(+), 19 deletions(-) >> >> diff --git a/include/exec/memattrs.h b/include/exec/memattrs.h >> index 9fb98bc1ef..1333a34cb3 100644 >> --- a/include/exec/memattrs.h >> +++ b/include/exec/memattrs.h >> @@ -43,7 +43,7 @@ typedef struct MemTxAttrs { >> * (see MEMTX_ACCESS_ERROR). >> */ >> unsigned int memory:1; >> - /* Requester ID (for MSI for example) */ >> + /* Requester ID (for MSI for example) or cpu_index for debug */ >> unsigned int requester_id:16; > > If we want to provide a requester ID for memory transactions we > should provide it always, not just for debug. That way gic_get_current_cpu() > and similar code can unconditionally use requester_id and never needs > to look at current_cpu. (We would also need to figure out how we want > to parcel out requester_ids in the system, so that PCI requester IDs > don't clash with CPU requester IDs.) We could have a requester_type field (0 for CPU, 1 for PCI for now)? > > -- PMM -- Alex Bennée
