Re: [PATCH v2 00/25] misc: Use explicit endian LD/ST API

[Richard Henderson]

On 10/4/24 09:30, Philippe Mathieu-Daudé wrote:
> Philippe Mathieu-Daudé (25):
>    gdbstub/helpers: Have ldtul_p() definition use ldn_p()
>    target/hexagon: Replace ldtul_p() -> ldl_p()
>    target/alpha: Replace ldtul_p() -> ldq_p()
>    target/s390x: Replace ldtul_p() -> ldq_p()
>    gdbstub/helpers: Introduce ldtul_$endian_p() helpers
>    target/alpha: Use explicit little-endian LD/ST API
>    target/hexagon: Use explicit little-endian LD/ST API
>    hw/i386: Use explicit little-endian LD/ST API
>    target/i386: Use explicit little-endian LD/ST API
>    target/avr: Use explicit little-endian LD/ST API
>    linux-user/i386: Use explicit little-endian LD/ST API
>    target/loongarch: Use explicit little-endian LD/ST API
>    target/sh4: Use explicit little-endian LD/ST API
>    target/tricore: Use explicit little-endian LD/ST API
>    target/rx: Use explicit little-endian LD/ST API
>    target/riscv: Use explicit little-endian LD/ST API
>    hw/m68k: Use explicit big-endian LD/ST API
>    target/m68k: Use explicit big-endian LD/ST API
>    hw/sparc: Use explicit big-endian LD/ST API
>    target/sparc: Use explicit big-endian LD/ST API
>    target/hppa: Use explicit big-endian LD/ST API
>    hw/s390x: Use explicit big-endian LD/ST API
>    target/s390x: Use explicit big-endian LD/ST API
>    target/openrisc: Use explicit big-endian LD/ST API
>    hw/ppc/e500: Use explicit big-endian LD/ST API

The sh4, rx, and riscv targets *can* support multiple endianness.

While we removed sh4eb for system mode, we still support sh4eb-linux-user, and therefore 
the target/sh4 patch affecting gdbstub is wrong.

RX sets endianness via a pin sampled at reset; if we ever implement this, it would be via 
a property on the cpu.  RISCV sets endianness via a couple of bits in MSTATUS; system mode 
would always use little-endian, but riscv64eb-user isn't out of the question.

While we have never supported rx or riscv in big-endian, but there's no reason that we 
can't, and those target/ patches make things harder. Since target/ will *always* have 
TARGET_BIG_ENDIAN available, I don't see that we're saving anything there.


r~