Re: [PATCH 20/20] target/loongarch: Add linux-user emulation support

[Peter Maydell]

On Mon, 28 Jun 2021 at 13:05, Song Gao <gaosong@loongson.cn> wrote:
>
> Add files to linux-user/loongarch64
> Add file to default-configs
> Add loongarch to target/meson.build
>
> Signed-off-by: Song Gao <gaosong@loongson.cn>
> ---
>  MAINTAINERS                                        |   1 +
>  default-configs/targets/loongarch64-linux-user.mak |   4 +
>  include/elf.h                                      |   2 +
>  linux-user/elfload.c                               |  58 ++++
>  linux-user/loongarch64/cpu_loop.c                  | 177 ++++++++++++
>  linux-user/loongarch64/signal.c                    | 193 +++++++++++++
>  linux-user/loongarch64/sockbits.h                  |   1 +
>  linux-user/loongarch64/syscall_nr.h                | 307 
> +++++++++++++++++++++
>  linux-user/loongarch64/target_cpu.h                |  36 +++
>  linux-user/loongarch64/target_elf.h                |  14 +
>  linux-user/loongarch64/target_fcntl.h              |  12 +
>  linux-user/loongarch64/target_signal.h             |  28 ++
>  linux-user/loongarch64/target_structs.h            |  49 ++++
>  linux-user/loongarch64/target_syscall.h            |  46 +++
>  linux-user/loongarch64/termbits.h                  | 229 +++++++++++++++
>  linux-user/syscall_defs.h                          |   8 +-
>  meson.build                                        |   2 +-
>  qapi/machine-target.json                           |   4 +-
>  target/loongarch/meson.build                       |  19 ++
>  target/meson.build                                 |   1 +
>  20 files changed, 1185 insertions(+), 6 deletions(-)

This is a massive patch that would benefit from being split up
into multiple smaller patches.

I'm told by a kernel developer that loongarch hasn't yet been
accepted into the Linux kernel mainline. Until it has been, the
syscall ABI for it is not yet stable, so we won't be able to take
the linux-user patches for it yet. (We have been burned in the
past by taking linux-user architecture support patches without
realizing they weren't for a stable ABI, and then being out of
sync with the eventual upstream kernel ABI that was accepted.)

We can certainly do code review in the meantime, though.

thanks
-- PMM