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

[Gustavo Zacarias]

On 10/17/2014 07:47 PM, Arnout Vandecappelle wrote:

>> 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)?

The only shared code in qemu for user vs. system is just basically CPU
emulation.
For system you've got all of the hardware (audio/ hw/ net/ directories
and so on) which isn't used by user at all.
For user it deals with what we can call "ABI" (userland, linux-user/ dir
in qemu) which isn't used by system at all, and has arch bits as well.
When there are system emulations broken with the latest version of qemu
it isn't necessarily a problem with the cpu emulation, the same can
happen to user emulation without affecting system.
So if you're like 100% sure user both will work right if system does for
X version go ahead, i don't think it's a safe assumption.
Just google around a bit:
https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1284344
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=668658
Regards.