Re: qemuarm: should it really have TUNE_ARCH armv5te?

[Martin Jansa <martin.jansa@gmail.com>]

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On Wed, Sep 12, 2012 at 03:33:03PM +0100, Richard Purdie wrote:
> On Tue, 2012-09-11 at 15:01 +0200, Martin Jansa wrote:
> > Hi,
> > 
> > when building spitz and qemuarm (both produces packages in armv5te feed)
> > resulting packages are tuned with -mtune=xscale (when built for spitz) 
> > or -mtune=arm926ej-s (when built for qemuarm).
> > 
> > From
> > https://bugzilla.yoctoproject.org/show_bug.cgi?id=1916#c5
> > Firstly, if you go changing the tune parameters in a given machine,
> > you are expected to use a different PACKAGE_ARCH. If you do that, you
> > will get a different package feed for the different binaries,
> > different WORKDIR and so on. This was always the way the package
> > architectures was intended to work and nothing has changed there. Yes,
> > you as the user changing various variables can create inconsistent
> > package feeds. There are 101 ways you can do that, the simple answer
> > is just don't. We're therefore unlikely to add MACHINE to DEPLOY_DIR
> > or remove PACKAGE_ARCH, please just use it as its intended.
> > 
> > Does qemuarm use oe-core as it's intended?
> > 
> > Shouldn't spitz produce something like armv5te-xscale and qemuarm armv5te-arm926ejs?
> > It would cause all recipes to build again (cannot share armv5te feed anymore),
> > but at least it would build it and user will really get it on target, right now
> > opkg upgrade can download some packages with xscale some with arm926ej-s.
> > 
> > $ ~/bitbake/bin/bitbake-diffsigs
> >   stamps.1347348910/spitz/armv5te-oe-linux-gnueabi/linux-libc-headers-3.4.3-r0.do_configure.sigdata.04b364a15889fcff7502614f1c116abc
> >   stamps.1347348910/qemuarm/armv5te-oe-linux-gnueabi/linux-libc-headers-3.4.3-r0.do_configure.sigdata.656f0583be969b427f040f2e143bcb14
> >   basehash changed from 7fe9c0a3455dac20ba6a90ed337b097e to d8dd2ff8613d0aafe60bef1a1e9469a1
> >   Variable TUNE_CCARGS value changed from
> >   ${@bb.utils.contains("TUNE_FEATURES", "armv5", "-march=armv5${ARMPKGSFX_THUMB}${ARMPKGSFX_DSP}", "", d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "armv4", "-march=armv4${ARMPKGSFX_THUMB}", "", d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "thumb", "${ARM_THUMB_M_OPT}", "", d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "no-thumb-interwork", "-mno-thumb-interwork", "-mthumb-interwork", d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "vfp", bb.utils.contains("TUNE_FEATURES", "callconvention-hard", "-mfloat-abi=hard", "-mfloat-abi=softfp", d), "" ,d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "xscale", "-mtune=xscale", "", d)}
> >   to
> >   ${@bb.utils.contains("TUNE_FEATURES", "armv5", "-march=armv5${ARMPKGSFX_THUMB}${ARMPKGSFX_DSP}", "", d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "armv4", "-march=armv4${ARMPKGSFX_THUMB}", "", d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "thumb", "${ARM_THUMB_M_OPT}", "", d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "no-thumb-interwork", "-mno-thumb-interwork", "-mthumb-interwork", d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "vfp", bb.utils.contains("TUNE_FEATURES", "callconvention-hard", "-mfloat-abi=hard", "-mfloat-abi=softfp", d), "" ,d)}
> >   ${@bb.utils.contains("TUNE_FEATURES", "arm926ejs", "-mtune=arm926ej-s", "", d)}
> > 
> 
> This is a tricky one. As others have mentioned, this is a tune
> parameter, not an arch one and as such the binaries are compatible with
> each other although they potentially are compiled differently with
> different optimisations.
> 
> As such, mixing the feeds is permitted and will not cause any real world
> usage problem. As you point out, sstate is much more sensitive to this
> kind of change and is correctly deciding the output is different though.
> 
> I think my preferred approach would be to have the tune files do
> something like:
> 
> -mtune=${ARMV5TEDEFAULTTUNE}
> 
> and then the user can set ARMV5DEFAULTTUNE to whatever the believe is a
> appropriate. This would result in the package feed at least having a
> consistent state of one tune and sstate would be happy. It then becomes
> a distro policy decision which is what it should be. ARMV5TEDEFAULTTUNE
> would default to the current values meaning the distro would then just
> do:
> 
> ARMV5TEDEFAULTTUNE_poky = "xscale"
>
> and hence make their decision. Of course the distro could also decide to
> split the package architectures up which is equally fine.
> 
> Does something like that sound like it would work?

My solution seems to be a bit more flexible then this.

-- 
Martin 'JaMa' Jansa     jabber: Martin.Jansa@gmail.com

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