Re: [gentoo-dev] [PMS] [PATCH] Correct the definition of ESYSROOT as EPREFIX isn't always applicable

[Alexis Ballier]

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On Wed, 31 Jul 2019 21:40:19 +0100

James Le Cuirot <chewi@g.o> wrote:



> On Wed, 31 Jul 2019 15:51:58 +0200
> Alexis Ballier <aballier@g.o> wrote:
>
> > On Tue, 30 Jul 2019 23:26:27 +0100
> > James Le Cuirot <chewi@g.o> wrote:
> >
> > > > Admittedly without a full understanding of the problem, but this
> > > > looks wrong to me: SYSROOT, EPREFIX and BROOT are only relevant
> > > > in build phases (src_*); (EPREFIX is a little special here but
> > > > mostly for convenience). ROOT is only relevant in pkg_* phases.
> > > > I don't see how this can work. Say I build a binpkg with ROOT=/
> > > > then use that binpkg with ROOT=/somewhere, you can't go back
> > > > and change SYSROOT.
> > >
> > > ROOT is used to determine ESYSROOT, not the other way around. As
> > > you say, (E)SYSROOT is only relevant in src phases so it doesn't
> > > matter if ROOT has changed when installing a binpkg.
> >
> > I am missing something here: You are making ESYSROOT depend on the
> > value of ROOT, so how can it not matter ?
>
> What I am trying to say (somewhat unsuccessfully!) is that the value
> of (E)SYSROOT only changes how the package is built, not what the
> resulting package looks like. It's where all the headers and libraries
> are sourced from at build time, which is irrelevant at runtime.


err, SYSROOT does change what the resulting package looks like: it

defines ABI (headers and needed entries for example).



> So why does ROOT affect it? Normally you install the packages for
> BDEPEND, DEPEND, and RDEPEND to the same location. If BDEPEND and
> RDEPEND are installed to different locations (ROOT!=/) then DEPEND
> will almost always be installed to one of the other two. If either of
> those two locations is prefixed then we need the prefix for DEPEND's
> location to match, otherwise it wouldn't actually be the same
> location. Using ROOT allows us to figure this out automatically in a
> way that covers all sensible use cases and avoids accidentally
> falling into an unsupported case.




So, now let's simplify this a bit and forget about prefix and crossdev

for a moment. Say I am building an atom chroot (for nfs root) on an

haswell desktop. I set ROOT=SYSROOT=/atomchroot. My desktop has CFLAGS

for haswell, and I have atom CFLAGS in

/atomchroot/etc/portage/make.conf. When I build something and portage

installs a BDEPEND to /, I want it to use my / configuration, and when

it is in /atomchroot I want it to use the configuration from there.

emerge has command line options to do that but I am not sure if this is

properly specified in PMS.





Now, say I am doing the same on a prefix haswell desktop. With your

algorithm, we have SYSROOT==ROOT so ESYSROOT is EPREFIX/SYSROOT.

However, what I want is a normal chroot with EPREFIX=/ here, so when

should one use ESYSROOT in an ebuild in that case ? where does this

EPREFIX comes from by the way ?





To me, this looks more of a general problem of defining where the

configuration is taken from, so that we can set EPREFIX independently

if it is SYSROOT or BROOT.







> I hope that's clearer.


Sorry :-(

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