Re: [PATCH v7 11/20] target/riscv/cpu: add misa_ext_info_arr[]

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 30/6/23 12:08, Daniel Henrique Barboza wrote:
> Next patch will add KVM specific user properties for both MISA and
> multi-letter extensions. For MISA extensions we want to make use of what
> is already available in misa_ext_cfgs[] to avoid code repetition.
> 
> misa_ext_info_arr[] array will hold name and description for each MISA
> extension that misa_ext_cfgs[] is declaring. We'll then use this new
> array in KVM code to avoid duplicating strings. Two getters were added
> to allow KVM to retrieve the 'name' and 'description' for each MISA
> property.
> 
> There's nothing holding us back from doing the same with multi-letter
> extensions. For now doing just with MISA extensions is enough.
> 
> It is worth documenting that even using the __bultin_ctz() directive to
> populate the misa_ext_info_arr[] we are forced to assign 'name' and
> 'description' during runtime in riscv_cpu_add_misa_properties(). The
> reason is that some Gitlab runners ('clang-user' and 'tsan-build') will
> throw errors like this if we fetch 'name' and 'description' from the
> array in the MISA_CFG() macro:
> 
> ../target/riscv/cpu.c:1624:5: error: initializer element is not a
>                                compile-time constant
>      MISA_CFG(RVA, true),
>      ^~~~~~~~~~~~~~~~~~~
> ../target/riscv/cpu.c:1619:53: note: expanded from macro 'MISA_CFG'
>      {.name = misa_ext_info_arr[MISA_INFO_IDX(_bit)].name, \
>               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
> 
> gcc and others compilers/builders were fine with that change. We can't
> ignore failures in the Gitlab pipeline though, so code was changed to
> make every runner happy.
> 
> As a side effect, misa_ext_cfg[] is no longer a 'const' array because
> it must be set during runtime.
> 
> Suggested-by: Andrew Jones <ajones@ventanamicro.com>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>   target/riscv/cpu.c | 110 +++++++++++++++++++++++++++++++++------------
>   target/riscv/cpu.h |   7 ++-
>   2 files changed, 88 insertions(+), 29 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>