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Re: [libvirt] [PATCH 4/5] domain conf: Support multiple <console> devices



On Wed, Jul 14, 2010 at 03:44:55PM -0400, Cole Robinson wrote:
> Change console handling to a proper device list, as done for other
> character devices. Even though certain drivers can actually handle multiple
> consoles, for now just maintain existing behavior where possible.
> 
> Signed-off-by: Cole Robinson <crobinso redhat com>

[snip]

> -        chr->target.port = 0;
> -        /*
> -         * For HVM console actually created a serial device
> -         * while for non-HVM it was a parvirt console
> -         */
> -        if (STREQ(def->os.type, "hvm")) {
> -            if (def->nserials != 0) {
> -                virDomainChrDefFree(chr);
> -            } else {
> -                if (VIR_ALLOC_N(def->serials, 1) < 0) {
> +        chr->target.port = i;
> +
> +        /* Back compat handling for the first console device */
> +        if (i == 0) {
> +            /*
> +            * For HVM console actually created a serial device
> +            * while for non-HVM it was a parvirt console
> +            */
> +            if (STREQ(def->os.type, "hvm")) {
> +                if (def->nserials != 0) {
>                      virDomainChrDefFree(chr);
> -                    goto no_memory;
> +                } else {
> +                    if (VIR_ALLOC_N(def->serials, 1) < 0) {
> +                        virDomainChrDefFree(chr);
> +                        goto no_memory;
> +                    }
> +                    def->nserials = 1;
> +                    def->serials[0] = chr;
> +                    chr->deviceType = VIR_DOMAIN_CHR_DEVICE_TYPE_SERIAL;
>                  }
> -                def->nserials = 1;
> -                def->serials[0] = chr;
> -                chr->deviceType = VIR_DOMAIN_CHR_DEVICE_TYPE_SERIAL;
> +            } else {
> +                def->consoles[def->nconsoles++] = chr;
>              }
>          } else {
> -            def->console = chr;
> +            def->consoles[def->nconsoles++] = chr;
>          }
>      }

This is where we get into a bit of a mess with back compatability,
when combined with the later DefFormat code.

The original requirement is that a <console> element generates
a <serial> element for HVM guests. In the original code we throw
away the virDomainChrDef for the console, since we re-generate
it at format time if nconsoles==0.  This hack can't work anymore
with multiple consoles. Since if we have 2 consoles in the XML
and throw away console 0, we have nconsoles==1 during DefFormat
and thus won't re-generate the original console 0. To further
complicate life, we don't want todo any of this <serial> compat
code this at all if console 0 is a virtio console.


> @@ -5496,9 +5512,10 @@ virDomainChrDefFormat(virBufferPtr buf,
>          return -1;
>      }
>  
> -    /* Compat with legacy  <console tty='/dev/pts/5'/> syntax */
>      virBufferVSprintf(buf, "    <%s type='%s'",
>                        elementName, type);
> +
> +    /* Compat with legacy  <console tty='/dev/pts/5'/> syntax */
>      if (def->deviceType == VIR_DOMAIN_CHR_DEVICE_TYPE_CONSOLE &&
>          def->type == VIR_DOMAIN_CHR_TYPE_PTY &&
>          !(flags & VIR_DOMAIN_XML_INACTIVE) &&

Since we're allowing multiple <console> now, we should restrict this
hack to just the first one.

> @@ -6213,9 +6230,10 @@ char *virDomainDefFormat(virDomainDefPtr def,
>              goto cleanup;
>  
>      /* If there's a PV console that's preferred.. */
> -    if (def->console) {
> -        if (virDomainChrDefFormat(&buf, def->console, flags) < 0)
> -            goto cleanup;
> +    if (def->nconsoles) {
> +        for (n = 0 ; n < def->nconsoles ; n++)
> +            if (virDomainChrDefFormat(&buf, def->consoles[n], flags) < 0)
> +                goto cleanup;
>      } else if (def->nserials != 0) {
>          /* ..else for legacy compat duplicate the first serial device as a
>           * console */

This logic can't work anymore.


What I think we need todo is to remove the hacks in both the Parse and
Format methods.  Then add one single hack for the parse method which
simply adds a matching <serial> device if nserial==0 and the console
device type is serial. 

Regards,
Daniel
-- 
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