Re: drjones@redhat.com, vkuznets@redhat.com, leiwang@redhat.com, wshi@redhat.com

[George Dunlap <george.dunlap@eu.citrix.com>]

On 04/24/2014 09:44 AM, Ian Campbell wrote:
> On Thu, 2014-04-24 at 08:14 +0800, Lingfei Kong wrote:
>> Maybe another solution is to change the xl command to adapt this.
> Feel free to propose a patch but I suspect this would involve too much
> surgery to the config file parser.
>
>>   On
>> RHEL5 xen hypervisor, I can create a guest with `xm create hvm.cfg
>> cpus="0-3"`. As a user I prefer this method, because this will be
>> consistent with it's config file and it is strange to use ' to enclose
>> the parameters.
> That is perfectly normal shell quoting behaviour, nothing strange about
> it IMHO.

Well having the config file syntax include quotes and brackets is 
natural.  The fact that the shell interprets quotes and brackets is also 
natural.  But the combination of the two leads to a rather unexpected 
and clunky user interface.

Unfortunately I'm not sure what we can really do at this point to 
maintain the general flexibility while avoiding backticks.  We might be 
able to modify the parser for specific cases, such as the cpus one, to 
tolerate 'cpus=0-3' rather than the canonical 'cpus="0-3"'. But in the 
general case it would require re-writing the config format such that it 
can be written without requiring any characters treated specially by the 
shell; that's just a bit more work than it's really worth, I think.

  -George