Re: [Qemu-devel] [PATCH v3 2/2] semihosting: add --semihosting-config arg sub-argument

[Peter Maydell]

On 8 May 2015 at 12:41, Leon Alrae <address@hidden> wrote:
> Add new "arg" sub-argument to the --semihosting-config allowing to pass
> multiple input argument separately. It is required for example by UHI
> semihosting to construct argc and argv.
>
> Signed-off-by: Leon Alrae <address@hidden>
> ---
>  include/exec/semihost.h | 12 ++++++++++++
>  qemu-options.hx         | 19 ++++++++++++++-----
>  vl.c                    | 33 +++++++++++++++++++++++++++++++++
>  3 files changed, 59 insertions(+), 5 deletions(-)
>
> diff --git a/include/exec/semihost.h b/include/exec/semihost.h
> index c2f0bcb..6e4e8c0 100644
> --- a/include/exec/semihost.h
> +++ b/include/exec/semihost.h
> @@ -36,9 +36,21 @@ static inline SemihostingTarget 
> semihosting_get_target(void)
>  {
>      return SEMIHOSTING_TARGET_AUTO;
>  }
> +
> +static inline const char *semihosting_get_arg(int i)
> +{
> +    return NULL;
> +}
> +
> +static inline int semihosting_get_argc(void)
> +{
> +    return 0;
> +}
>  #else
>  bool semihosting_enabled(void);
>  SemihostingTarget semihosting_get_target(void);
> +const char *semihosting_get_arg(int i);
> +int semihosting_get_argc(void);
>  #endif
>
>  #endif
> diff --git a/qemu-options.hx b/qemu-options.hx
> index ec356f6..84ae6c2 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -3296,14 +3296,23 @@ STEXI
>  Enable semihosting mode (ARM, M68K, Xtensa only).
>  ETEXI
>  DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
> -    "-semihosting-config [enable=on|off,]target=native|gdb|auto   
> semihosting configuration\n",
> +    "-semihosting-config 
> [enable=on|off][,target=native|gdb|auto][,arg=str[,...]]\n" \
> +    "                semihosting configuration\n",
>  QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32)
>  STEXI
> address@hidden -semihosting-config [enable=on|off,]target=native|gdb|auto
> address@hidden -semihosting-config 
> [enable=on|off][,target=native|gdb|auto][,arg=str[,...]]
>  @findex -semihosting-config
> -Enable semihosting and define where the semihosting calls will be addressed,
> -to QEMU (@code{native}) or to GDB (@code{gdb}). The default is @code{auto}, 
> which means
> address@hidden during debug sessions and @code{native} otherwise (ARM, M68K, 
> Xtensa only).
> +Enable and configure semihosting (ARM, M68K, Xtensa only).
> address@hidden @option
> address@hidden address@hidden|gdb|auto}
> +Defines where the semihosting calls will be addressed, to QEMU 
> (@code{native})
> +or to GDB (@code{gdb}). The default is @code{auto}, which means @code{gdb}
> +during debug sessions and @code{native} otherwise.
> address@hidden address@hidden,address@hidden,...
> +Allows the user to pass input arguments, can be used multiple times to build 
> up
> +a list. This is a replacement for the old-style -kernel/-append method of
> +passing a command line to semihosting.
> address@hidden table

You need to say how this interacts with the -kernel/-append option
(ie what happens if you specify both). Also, you haven't actually
changed anything so at the moment -arg doesn't do anything.

The only semihosting target in-tree which cares about arguments
at the moment is ARM.

Ideally semihost.h's "get me the command line" function(s) should
handle "use -arg if present, fall back to -kernel + -append if not"
so the target specific semihosting code doesn't need to care.

thanks
-- PMM