Re: [Qemu-devel] '.' IDs and certain names breaks -global and -set

[Alistair Francis]

On Wed, Apr 9, 2014 at 9:58 PM, Peter Crosthwaite
<address@hidden> wrote:
> On Wed, Apr 9, 2014 at 7:56 PM, Markus Armbruster <address@hidden> wrote:
>> We have a number of device model names containing '.'.  They're unusable
>> with -global.  That's because "-global A.B.C=foo" gets parsed as
>>
>>     driver = "A"
>>     property = "B.C"
>>     value = "foo".
>>
>> Wrong when the device model name is really A.B and the property is C,
>> e.g. "-global cfi.pflash01.name".
>>
>> Related problem: QemuOpts ID may contain '.'.  Such IDs are in fact
>> common practice.  Unfortunately, they're unusable with -set.  For
>> instance, -set A.B.C.D=foo gets parsed as
>>
>>     group = "A"
>>     id = "B"
>>     arg = "C.D"
>>     value = "foo"
>>
>> Wrong when the id is really B.C and the arg is D, e.g. "-device
>> isa-serial,id=s.0 -set device.s.0.chardev=c0".  This issue isn't limited
>> to devices.
>>
>> Related historical problem: commit b560a9a.
>>
>> Possible solutions:
>>
>> * Outlaw '.' in QemuOpts parameter names (and thus device model names
>>   and property names, because QemuOpts is a major way for users to
>>   specify them).
>>
>
> I like the "."s because they mean "this is where the vendor stops and
> the IP name starts". Whereas "-" just delimits multiple words. We seem
> to be running our of characters however with these overloading
> problems. But AFAICT ":" is largely unused (within this context
> anyway). So how about:
>
> "-" seperates multiple words in a name
> ":" splits logical groupings of multiple words as appropriate ( e.g.
> some-vendor:their-device )
> "," demilits multiple command line arguments
> "." accesses property within an object
> "/" walks the canonical path
>
> I do also need to confess to my alternate agenda of device tree driven
> QEMU - I am still parsing device trees and directly mapping the
> compatible strings to QOM type names for machine creation. Ambiguity
> of "-" as meaning the "," or the "-" is hard to deal with.
>
> Regards,
> Peter
>
>> * Resolve the syntactic ambiguity semantically (ugh)
>>
>> * Extend the syntax of -global and -set to let users avoid the issue, or
>>   replace them outright
>>
>> * Use the old ostrich algorithm
>>
>> Andreas, what restrictions does QOM place on QOM path component names?
>> No '/', obviously.  Anything else?
>>
>

What is the consensus with this? I like Peter's naming suggestions as
they are straight
forward and don't break any compatibility.