[Qemu-devel] 答复： Re: [PATCH] chardev: Add 'help' option to print all available chardev backend types

[Lin Ma]

>>> Marc-André Lureau <address@hidden> 8/17/2016 1:25 上午 >>>
>Hi
>
>On Tue, Aug 16, 2016 at 9:18 PM Lin Ma <address@hidden> wrote:
>
>> Signed-off-by: Lin Ma <address@hidden>
>> ---
>>  qemu-char.c     | 21 ++++++++++++++++-----
>>  qemu-options.hx |  3 +++
>>  2 files changed, 19 insertions(+), 5 deletions(-)
>>
>> diff --git a/qemu-char.c b/qemu-char.c
>> index 8a0ab05..8a7aef3 100644
>> --- a/qemu-char.c
>> +++ b/qemu-char.c
>> @@ -39,6 +39,7 @@
>>  #include "io/channel-file.h"
>>  #include "io/channel-tls.h"
>>  #include "sysemu/replay.h"
>> +#include "qemu/help_option.h"
>>
>>  #include <zlib.h>
>>
>> @@ -3877,16 +3878,26 @@ CharDriverState *qemu_chr_new_from_opts(QemuOpts
>> *opts,
>>        const char *id = qemu_opts_id(opts);
>>        char *bid = NULL;
>>
>> -    if (id == NULL) {
>> -        error_setg(errp, "chardev: no id specified");
>> -        goto err;
>> -    }
>> -
>>        if (qemu_opt_get(opts, "backend") == NULL) {
>>                error_setg(errp, "chardev: \"%s\" missing backend",
>>                                       qemu_opts_id(opts));
>>                goto err;
>>        }
>> +
>> +    if (is_help_option(qemu_opt_get(opts, "backend"))) {
>> +        fprintf(stderr, "Available chardev backend types:\n");
>> +        for (i = backends; i; i = i->next) {
>> +                cd = i->data;
>> +                fprintf(stderr, "%s\n", cd->name);
>> +        }
>> +        exit(!is_help_option(qemu_opt_get(opts, "backend")));
>> +    }
>> +
>> +    if (id == NULL) {
>> +        error_setg(errp, "chardev: no id specified");
>> +        goto err;
>> +    }
>> +
>>        for (i = backends; i; i = i->next) {
>>                cd = i->data;
>>
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index a71aaf8..379f7a5 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -2148,6 +2148,7 @@ The general form of a character device option is:
>>  ETEXI
>>
>>  DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
>> +    "-chardev help\n"
>>        "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
>>        "-chardev
>> socket,id=id[,host=host],port=port[,to=to][,ipv4][,ipv6][,nodelay][,reconnect=seconds]\n"
>>        "
>>  [,server][,nowait][,telnet][,reconnect=seconds][,mux=on|off]\n"
>> @@ -2213,6 +2214,8 @@ Backend is one of:
>>  @option{spiceport}.
>>  The specific backend will determine the applicable options.
>>
>> +Use "-chardev help" to print all available chardev backend types.
>> +
>>
>
>How different is it from the list in qemu -help ? Why duplicate that list
>with less informations (arguments and details) ? Do you expect it to be
>easily machine readable?
>
No special reason, Just add 'help' option to make it more friendly, like the
output of '-watchdog help' or '-tpmdev help', Sometimes I forget the chardev
backend names which I want to try, I'd like to have a very easy&fast way to
get the backend list :-).
 
Various backends have various arguments, Printing all of them causes the
complex output, that was my thought before I send the patch.
Now...yes, it makes sense that including the arguments in output, I can add
them if the patch's idea is acceptable.
 
 
Lin