On 4/10/24 18:41, Peter Maydell wrote:
On Fri, 4 Oct 2024 at 17:22, Philippe Mathieu-Daudé <phi...@linaro.org> wrote:Introduce the CPUClass::is_big_endian() handler and its common default. Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org> --- include/hw/core/cpu.h | 3 ++- hw/core/cpu-common.c | 7 +++++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index 04e9ad49968..22ef7a44e86 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -150,6 +150,7 @@ struct CPUClass { ObjectClass *(*class_by_name)(const char *cpu_model); void (*parse_features)(const char *typename, char *str, Error **errp); + bool (*is_big_endian)(CPUState *cpu); bool (*has_work)(CPUState *cpu); int (*mmu_index)(CPUState *cpu, bool ifetch); int (*memory_rw_debug)(CPUState *cpu, vaddr addr,What does this actually mean, though? Arm for instance has multiple different kinds of "big-endian" depending on the CPU: both BE32 and BE8, and data-endianness not necessarily being the same as instruction-endianness.
This is to be used in the data bus (I was wondering whether using 'data' in the method name).
This series doesn't introduce any users of this new API. It's hard to say without seeing what the intended use is, but I would expect that probably they would want to be testing something else, depending on what they're trying to do.
I'm trying to split my branch in "~20 patches series"; I should post example of API consumers in a few days. First conversion is the cpu_in/out() API in system/ioport.c, I'll try to post it ASAP so we can discuss there.
It's pretty uncommon for anything out in the system to want to know what endianness a runtime-configurable CPU happens to be set to, because in real hardware a device has no way to tell. (This is why cpu_virtio_is_big_endian() is named the way it is -- to discourage anybody from trying to use it outside the virtio devices where we need it for legacy "the spec wasn't written thinking about endianness very hard" reasons.)
I'm trying to convert implicit knowledge of target endianness to explicit one, propagated as argument from the machine.
