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

[Liviu Ionescu]

> On 01 Apr 2015, at 16:18, Leon Alrae <address@hidden> wrote:
> 
> ... 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 checked the differences between my fork and the master branch (SourceTree for 
Mac is a great git tool!), and I can summarise my changes:

- in qemu-options.hx I added -semihosting_cmdline

        DEF("semihosting-cmdline", HAS_ARG, QEMU_OPTION_semihosting_cmdline,
        "-semihosting-cmdline [string]   semihosting command line\n",
        QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32)

- in vl.c I defined I defined qemu_semihosting_cmdline_opts

static QemuOptsList qemu_semihosting_cmdline_opts = {
    .name = "semihosting-cmdline",
    .implied_opt_name = "cmdline",
    .merge_lists = true,
    .head = QTAILQ_HEAD_INITIALIZER(qemu_semihosting_cmdline_opts.head),
    .desc = {
         { /* end of list */ }
    },
};

- in vl.c I identify the "semihosting-cmdline", get the next option argument 
and store it in the cmdline option field:

            case QEMU_OPTION_semihosting_cmdline:
                opts = qemu_opts_parse(qemu_find_opts("semihosting-cmdline"),
                                           optarg, 0);
                if (opts != NULL) {
                    Error *local_err = NULL;
                    qemu_opt_set(opts, "cmdline", optarg, &local_err);
                }

- in target-arm/arm-semi.c, the initial code computed the semihosting command 
line by concatenating the kernel path and the kernel cmdline. the patched 
version first checks if -semihosting-cmdline is not null, and uses it as-is, 
otherwise it falls back to the kernel path and kernel cmdline.

the intention was to remain compatible with existing configurations, and I 
guess it was met.

access to semihosting cmdline is simple:

        opts = qemu_opts_find(qemu_find_opts("semihosting-cmdline"), NULL);
        cmdline = qemu_opt_get(opts, "cmdline");

https://sourceforge.net/p/gnuarmeclipse/qemu/ci/gnuarmeclipse-dev/tree/target-arm/arm-semi.c

- in hw/arm/cortexm.c, the equivalent of armv7m.c, the env->boot_info pointer 
must be initialised, otherwise the arm-semi.c code fails.

    /* Fill-in a minimalistic boot info, required for semihosting.  */
    cortexm_binfo.kernel_cmdline = kernel_cmdline;
    cortexm_binfo.kernel_filename = machine->kernel_cmdline;
    

    env->boot_info = &cortexm_binfo;


you can use these code snippets, or I can pack them in a patch, if the 
semihosting-cmdline solution is accepted in the master branch.


regards,

Liviu