Re: [Qemu-devel] [PATCH] move qemu-ga from bin to libexec dir, use $HELPERS

[Paolo Bonzini]

Il 21/02/2013 15:30, Michael Tokarev ha scritto:
> 21.02.2013 17:35, Paolo Bonzini wrote:
>> Il 16/02/2013 19:28, Michael Tokarev ha scritto:
>>> This patch does 3 things:
>>>
>>> 1. Renames HELPERS-y Makefile variable to HELPERS
>>> 2. Moves its definition from Makefile to configure
>>
>> I prefer to have more decisions in Makefile than configure, but this
>> wouldn't block the patch.  What we have now is a mess anyway.
> 
> What's the difference between checking for host OS type being
> in makefile or configure?

That you list all the build products in the Makefile, where they should be.

> Note that in this very case current condition is a bit wrong:
> it should not only depend on linux but also about presence of
> softmmu targets (which this patch fixes too).
> 
>>> 3. Moves qemu-ga binary from TOOLS to HELPERS.
>>>
>>> The effects are:
>>>
>>> 1. qemu-ga binary is now installed into libexecdir, not bindir.
>>> This is the main effect/motivation of this patch, -- this binary
>>> has no business being in a public binary directory, it is a system
>>> helper which must be run by a system startup script or some event
>>> daemon.
>>
>> There is one difference, and an important one: qemu-ga does appear in
>> system-wide configuration files, while qemu-bridge-helper does not.  In
>> this sense, qemu-ga is not a helper executable.
> 
> Well, it definitely is not a user-callable binary.

Since we do not ship udev rules, we are really shipping it for the user
to call it.  How it does that, we don't care.

> In that sence it is a
> "system helper" (as opposed to "qemu helper" for qemu-bridge-helper).  Ie,
> either sbin or libexec, but not bin.  There's no sbindir handling currently, 
> --
> neither in makefile nor in configure, only "TOOLS" and "HELPERS" variables.

sbindir would be more correct than libexecdir.

The latest fad for udev is to put helpers in $prefix/lib/udev (not
$libdir, because there's no 32/64-bit differentiation).

Perhaps the best solution is to add --with-qemu-ga-dir=... and default
it to $bindir.  Then distros that ship udev rules can move it to
/usr/lib/udev, distros that ship an initscript can move it to /usr/sbin
or wherever they prefer.

>> I have no idea how virtfs-proxy-helper would work, but I suspect that a
>> better design would have QEMU spawning it, just like qemu-bridge-helper.
> 
> QEMU can't spawn it, it is spawned in *guest* by a startup script or some
> event daemon (such as systemd or udev).

I'm talking about virtfs-proxy-helper.

Paolo