Re: [Qemu-devel] [RFC PATCH] vl.c: add -semihosting-config "arg" sub-argument

[Christopher Covington <cov@codeaurora.org>]

Hi Leon,

On 04/01/2015 09:18 AM, Leon Alrae wrote:
> Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
> ---
> Hi,
> 
> Continuing the discussion related to extending QEMU's command line with new
> argument allowing to pass semi-hosting input arguments to the guest program:
> https://lists.gnu.org/archive/html/qemu-devel/2015-03/msg05960.html
> 
> This simple patch adds "arg" sub-argument which in my opinion is flexible
> enough to satisfy semi-hosting interfaces which allocate buffers at runtime
> (so it is possible to pass any number of strings of any length) as well as the
> ones which have limited buffer for a single input string.
> 
> Highlights:
> 
> * arg can appear multiple times in -semihosting-config group of sub-arguments
>   and is used to create argc/argv.
> 
> * Single string cmdline can be still easily created:
>     static void concat_semihosting_args(char *buffer, int buffer_size,
>                                         const char *separator)
>     {
>         int i;
>         buffer[0] = '\0';
>         for (i = 0; i < semihosting_argc - 1; i++) {
>             pstrcat(buffer, buffer_size, semihosting_argv[i]);
>             pstrcat(buffer, buffer_size, separator);
>         }
>         pstrcat(buffer, buffer_size, semihosting_argv[i]);
>     }
> 
> * argv[0] is set by the first occurence of "arg" rather than taking the same
>   string from "-kernel". This might be required in cases where the path is too
>   long and semi-hosting app's buffer for the cmdline is fixed and small.
> 
> * No altering the parser itself, just traversing the -semihosting-config opts
>   and picking all arg strings.
> 
> * This patch doesn't fix the need of using double-commas if user want to have
>   a comma in the string.
> 
> If we agree on this new option then I would like to follow up with a clean up
> where we've got a semi-hosting specific structure rather than keep generating
> more semihosting_* variables (I skipped it in this patch to avoid generating
> clean up related noise in the diff).

I think the commit message and help text should include some information on
how this is different from -append and what the result is of specifying both
-append foo=a and -semihosting-config arg=foo=b.

Thanks,
Chris

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