Re: [Xen-devel] [PATCH RFC 3/4] libxl: implement channels via PV console rings attached to qemu

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Jun 11, 2014 at 09:24:28PM +0100, David Scott wrote:
> We extend the (internal) console type with a 'name' (string)
> which isn't used by the default built-in console 0.
> 
> For every channel we create a console, starting at index 1,
> which is handled by the qemu 'chardev' mechanism (ie has
> 'output=chardev:libxl-channel%d' in xenstore)
> 
> Signed-off-by: David Scott <dave.scott@xxxxxxxxxx>
> ---
>  tools/libxl/libxl_create.c           |   60 
> ++++++++++++++++++++++++++++++++++
>  tools/libxl/libxl_types_internal.idl |    1 +
>  2 files changed, 61 insertions(+)
> 
> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> index d015cf4..13a2a27 100644
> --- a/tools/libxl/libxl_create.c
> +++ b/tools/libxl/libxl_create.c
> @@ -361,11 +361,60 @@ static int init_console_info(libxl__device_console 
> *console, int dev_num)
>      console->devid = dev_num;
>      console->consback = LIBXL__CONSOLE_BACKEND_XENCONSOLED;
>      console->output = strdup("pty");
> +    /* console->name is NULL on normal consoles. Only 'channels' when mapped
> +       to consoles have a string name. */
>      if (!console->output)
>          return ERROR_NOMEM;
>      return 0;
>  }
>  
> +static int init_console_from_channel(libxl__gc *gc,
> +                                     libxl__device_console *console,
> +                                     int dev_num,
> +                                     libxl_device_channel *channel)
> +{
> +    const char *chardev;
> +    memset(console, 0x00, sizeof(libxl__device_console));

I suppose you should use libxl__device_console_init instead?

> +    console->devid = dev_num;
> +    console->consback = LIBXL__CONSOLE_BACKEND_IOEMU;
> +    if (!channel->name){
> +        LIBXL__LOG(CTX, LIBXL__LOG_ERROR,
> +                   "channel %d has no name", channel->devid);
> +        return ERROR_INVAL;
> +    }
> +    console->name = strdup(channel->name);

libxl__strdup, use NOGC if you don't want console->name gets freed.

> +    console->backend_domid = channel->backend_domid;
> +
> +    switch (channel->type) {
> +        case LIBXL_CHANNEL_TYPE_NONE:
> +        case LIBXL_CHANNEL_TYPE_PTY:
> +            /* No path is needed */
> +            break;
> +        case LIBXL_CHANNEL_TYPE_PATH:
> +        case LIBXL_CHANNEL_TYPE_SOCKET:
> +            if (!channel->path) {
> +                LIBXL__LOG(CTX, LIBXL__LOG_ERROR,
> +                           "channel %d has no path", channel->devid);
> +                return ERROR_INVAL;
> +            }
> +            break;
> +        default:
> +            /* We've forgotten to add the clause */
> +            LOG(ERROR, "%s: unknown channel type %d", __func__, 
> channel->type);
> +            return ERROR_INVAL;
> +    }
> +
> +    /* Use qemu chardev for every channel */
> +    chardev = libxl__sprintf(gc, "chardev:libxl-channel%d",
> +                                 channel->devid);
> +    if (!chardev) return ERROR_NOMEM;
> +    console->output = strdup(chardev);

libxl__strdup might be a better choice, so that you can ...

> +    if (!console->output) return ERROR_NOMEM;

... get rid of this line.


Wei.

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