[Buildroot] [PATCH 1/3] qemu-system: new package

[Arnout Vandecappelle <arnout@mind.be>]

On 16/10/14 15:53, Gustavo Zacarias wrote:
> On 10/15/2014 02:01 PM, Arnout Vandecappelle wrote:
> 
>>  Can you explain why not?
>>
>>  You cannot use different versions for qemu-user and qemu-system in a clean way
>> if they're not different packages. But host and target versions don't need to be
>> the same. At least, I see code in pkg-generic.mk to handle that.
> 
> Well, not really, for example try modifying package/e2fsprogs.mk:
> HOST_E2FSPROGS_VERSION = 1.42.13
> 
> And build both, see what happens.
> Even try a make source with that.

 Yeah, OK, you have to set the HOST_FOO_SOURCE explicitly as well due to a
little shortcoming in the infrastructure, but I don't think that should be a
showstopper.

> 
>>  And I do think we want to keep qemu-user and qemu-system at the same version,
>> right? Or does it happen that you need different versions for these as well?
>>
>>  The real question is how to make the version depend on the values in
>> BR2_PACKAGE_QEMU_CUSTOM_TARGETS. But that is not the concern of your patch.
> 
> No, that's a wrong assumption.
> For example qemu_mpc8544ds_defconfig doesn't work with the latest 2.1.2
> qemu, however other qemu ppc sample defconfigs do (in fact no 2.1.x
> version).

 Yes, you're right, the host-qemu version should be dictated by a config option,
not derived automatically.


> And the qemu config should dictate what's the best version for each -
> not necessarily the latest, you can't make host-qemu-user depend on that
> since it's a platform decision, not an arch one.
> If you want to stick with "the one that works for everything" you

 AFAIK nobody claims that there should be one version that works for everything
- possibly there should even be some version config option for the target qemu.
The only problem we see is to have a separate qemu-system and qemu-user package.


> potentially miss the opportunity for new arch and/or platform support.
> So even if target != host version is fixed/possible you'll still clash
> on host-qemu (user) vs. host-qemu (system) versions since you might want
> to do the perl module dance (original purpose of host-qemu) vs. platform
> emulation.

 This one I don't understand. If you need version 2.0.2 for host-qemu-system,
then surely you also need this version for host-qemu-user? So what is the point
of treating them as separate packages? Isn't it much easier to build qemu-user
and qemu-system in one shot (like how it's done for the target qemu)?


 Regards,
 Arnout


> It's nice to keep everything in one package, but it's not feasible to do
> so in a coherent way for this case in particular.
> If you can't get the leash out of the qemu version there's no point in
> building so for the emulation, sometimes you'll ship every single qemu
> config working, sometimes you wont - and that's my quarrel, everyone is
> perfect-this perfect-that but all of the sudden this would be acceptable?
> Like i said it would be the same as $RANDOM distro qemu.
> Regards.


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
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