Re: [PATCH v3 26/33] *-user: Deprecate and disable -p pagesize

[Ilya Leoshkevich]

On Tue, Jan 02, 2024 at 12:58:01PM +1100, Richard Henderson wrote:
> This option controls the host page size.  From the mis-usage in
> our own testsuite, this is easily confused with guest page size.
> 
> The only thing that occurs when changing the host page size is
> that stuff breaks, because one cannot actually change the host
> page size.  Therefore reject all but the no-op setting as part
> of the deprecation process.
> 
> Reviewed-by: Warner Losh <imp@bsdimp.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  docs/about/deprecated.rst |  7 +++++++
>  docs/user/main.rst        |  3 ---
>  bsd-user/main.c           |  9 +++++----
>  linux-user/main.c         | 11 ++++++-----
>  4 files changed, 18 insertions(+), 12 deletions(-)

[...]

> diff --git a/linux-user/main.c b/linux-user/main.c
> index 5f217cc2a8..9ba4dc5872 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -332,10 +332,11 @@ static void handle_arg_ld_prefix(const char *arg)
>  
>  static void handle_arg_pagesize(const char *arg)
>  {
> -    qemu_host_page_size = atoi(arg);
> -    if (qemu_host_page_size == 0 ||
> -        (qemu_host_page_size & (qemu_host_page_size - 1)) != 0) {
> -        fprintf(stderr, "page size must be a power of two\n");
> +    unsigned size, want = qemu_real_host_page_size();
> +
> +    if (qemu_strtoui(arg, NULL, 10, &size) || size != want) {
> +        error_report("Deprecated page size option cannot "
> +                     "change host page size (%u)", want);
>          exit(EXIT_FAILURE);

I wonder if this should rather be a warning for one release?

[...]