why "PREFERRED_PROVIDER_udev" and not "PREFERRED_PROVIDER_virtual/udev"?

why "PREFERRED_PROVIDER_udev" and not "PREFERRED_PROVIDER_virtual/udev"?

[Robert P. J. Day]

  i was going to extend section 3.3.17, "Using Virtual Providers",
with an intro example using "udev" until i realized that that example
doesn't use the "virtual/" notation. so ... why not? is there some
distinction between other components that use the "virtual/" prefix,
but a reason that one does not specify:

  PROVIDES = "virtual/udev"

rather than just:

  PROVIDES = "udev"

and then use the corresponding PREFERRED_PROVIDER_virtual/udev
notation?

rday

Re: [OE-core] why "PREFERRED_PROVIDER_udev" and not "PREFERRED_PROVIDER_virtual/udev"?

[Khem Raj]

On Mon, Aug 30, 2021 at 12:52 AM Robert P. J. Day <rpjday@crashcourse.ca> wrote:
>
>
>   i was going to extend section 3.3.17, "Using Virtual Providers",
> with an intro example using "udev" until i realized that that example
> doesn't use the "virtual/" notation. so ... why not? is there some
> distinction between other components that use the "virtual/" prefix,
> but a reason that one does not specify:
>
>   PROVIDES = "virtual/udev"
>
> rather than just:
>
>   PROVIDES = "udev"
>
> and then use the corresponding PREFERRED_PROVIDER_virtual/udev
> notation?

we also have VIRTUAL-RUNTIME_dev_manager which spans across systemd to mdev
so I guess we could but perhaps we already have this functionality
>
> rday
>
> 
>

Re: [OE-core] why "PREFERRED_PROVIDER_udev" and not "PREFERRED_PROVIDER_virtual/udev"?

[Robert P. J. Day]

On Mon, 30 Aug 2021, Khem Raj wrote:

> On Mon, Aug 30, 2021 at 12:52 AM Robert P. J. Day <rpjday@crashcourse.ca> wrote:
> >
> >
> >   i was going to extend section 3.3.17, "Using Virtual Providers",
> > with an intro example using "udev" until i realized that that example
> > doesn't use the "virtual/" notation. so ... why not? is there some
> > distinction between other components that use the "virtual/" prefix,
> > but a reason that one does not specify:
> >
> >   PROVIDES = "virtual/udev"
> >
> > rather than just:
> >
> >   PROVIDES = "udev"
> >
> > and then use the corresponding PREFERRED_PROVIDER_virtual/udev
> > notation?
>
> we also have VIRTUAL-RUNTIME_dev_manager which spans across systemd to mdev
> so I guess we could but perhaps we already have this functionality

  a followup, perhaps silly question -- is there anything special
about the "virtual/" prefix in the sense of being a provider? i mean,
other than being more aesthetically obvious?

rday

Re: [OE-core] why "PREFERRED_PROVIDER_udev" and not "PREFERRED_PROVIDER_virtual/udev"?

[Richard Purdie]

On Tue, 2021-08-31 at 04:27 -0400, Robert P. J. Day wrote:
> On Mon, 30 Aug 2021, Khem Raj wrote:
> 
> > On Mon, Aug 30, 2021 at 12:52 AM Robert P. J. Day <rpjday@crashcourse.ca> wrote:
> > > 
> > > 
> > >   i was going to extend section 3.3.17, "Using Virtual Providers",
> > > with an intro example using "udev" until i realized that that example
> > > doesn't use the "virtual/" notation. so ... why not? is there some
> > > distinction between other components that use the "virtual/" prefix,
> > > but a reason that one does not specify:
> > > 
> > >   PROVIDES = "virtual/udev"
> > > 
> > > rather than just:
> > > 
> > >   PROVIDES = "udev"
> > > 
> > > and then use the corresponding PREFERRED_PROVIDER_virtual/udev
> > > notation?
> > 
> > we also have VIRTUAL-RUNTIME_dev_manager which spans across systemd to mdev
> > so I guess we could but perhaps we already have this functionality
> 
>   a followup, perhaps silly question -- is there anything special
> about the "virtual/" prefix in the sense of being a provider? i mean,
> other than being more aesthetically obvious?

Not really, it just signifies particular groups like the libc example I mention
in another mail.

Cheers,

Richard

Re: [OE-core] why "PREFERRED_PROVIDER_udev" and not "PREFERRED_PROVIDER_virtual/udev"?

[Richard Purdie]

On Mon, 2021-08-30 at 03:52 -0400, Robert P. J. Day wrote:
>   i was going to extend section 3.3.17, "Using Virtual Providers",
> with an intro example using "udev" until i realized that that example
> doesn't use the "virtual/" notation. so ... why not? is there some
> distinction between other components that use the "virtual/" prefix,
> but a reason that one does not specify:
> 
>   PROVIDES = "virtual/udev"
> 
> rather than just:
> 
>   PROVIDES = "udev"
> 
> and then use the corresponding PREFERRED_PROVIDER_virtual/udev
> notation?

The "virtual/" namespace is just a way of namespacing some key dependencies
outside of the direct recipe namespace. 

virtual/libc is a better example and there are a few toolchain related ones.
There are several different libc implementations and virtual/libc just says you
want one without being specific.

Cheers,

Richard