[Buildroot] Can't use output/host/ as "SDK" with external toolchain

[Bryce Schober]

I just tried that, and I get the same results. Both the binutils symbolic
links and ext-toolchain-wrapper still use absolute paths. These patches
don't touch the logic used to assemble a full sysroot with the compiler and
buildroot host outputs in the same place.

It seems that the current importing and wrapping of any type of external
toolchain would have to be fundamentally re-worked in order to be
relocatable. It seems that two things would need to change:
1. Any symbolic links created would have to have any absolute paths
converted to relative.
2. Any paths used in the ext-toolchain-wrapper would have to be relative,
and the wrapper itself would have to determine the path to itself in order
to correctly exec the programs it wraps.

<><  <><  <><
Bryce Schober



On Tue, Jan 10, 2012 at 11:38 PM, Thomas De Schampheleire <
patrickdepinguin+buildroot at gmail.com> wrote:

> On Tue, Jan 10, 2012 at 9:22 PM, Bryce Schober <bryce.schober at gmail.com>
> wrote:
> > As I said in my original post, I am using an externally generated and
> > configured (and statically linked) crosstool-ng toolchain.
>
> I'm sorry, I read over that part.
>
> > I believe that it
> > is the buildroot import thereof that is at fault. Again, in summary:
> > 1. Buildroot generates absolute-pathed symbolic links to the external
> > binutils in output/host/usr/bin instead of copying them in.
> > 2. Buildroot's ext-toolchain-wrapper uses an absolute path for its
> sysroot
> > configuration.
> > 3. Buildroot's ext-toolchain-wrapper uses an absolute path for its binary
> > exec path.
> >
> > I realize that these problems are triggered by my specification of:
> > BR2_TOOLCHAIN_EXTERNAL_PATH="$(TOPDIR)/../my-ext-toolchain-dir/"
> > But I can't specify merely "../my-ext-toolchain-dir/" without breaking
> > things either.
> >
>
> Have you tried using BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD instead? This
> requires you to archive the crosstool-ng toolchain and specify it to
> buildroot. Buildroot will then extract it and unpack. The binutils
> will be copied in this case, and not symlinked.
>
> This is not possibly in stock buildroot. I have submitted patches for
> this a while ago, but they are not yet included. I think there was a
> comment by Thomas that I still have to fix. In the mean time, try
> using patches 1 and 2 of the following series:
> http://lists.busybox.net/pipermail/buildroot/2011-August/044779.html
>
> Best regards,
> Thomas
>
>
> >
> > On Tue, Jan 10, 2012 at 3:26 AM, Thomas De Schampheleire
> > <patrickdepinguin+buildroot at gmail.com> wrote:
> >>
> >> Hi Bryce,
> >>
> >> On Mon, Jan 9, 2012 at 11:54 PM, Bryce Schober <bryce.schober at gmail.com
> >
> >> wrote:
> >> > What I mean by "SDK" is the ability to compile external programs using
> >> > the
> >> > buildroot toolchain and libraries on any reasonably-compatible host.
> I'm
> >> > assuming that the toolchain itself is built properly static for its
> own
> >> > host
> >> > independence (which in my case, it is). Ideally the toolchain in the
> >> > output/host directory would be capable of standing alone, when built
> >> > properly
> >> >
> >> > I'm having two issues w/ archving the output/host dir for extraction
> and
> >> > usage in a different host directory. I'm using a custom-built
> >> > crosstool-ng
> >> > built externally and independent of buildroot.
> >> >
> >> > The external toolchain import results in three distinct problems that
> I
> >> > can
> >> > see:
> >> > 1. The symbolic links for binutils binaries in use absolute paths to
> >> > link to
> >> > the external toolchain instead of copying them in.
> >> > 2. The ext-toolchain-wrapper uses an absolute path for the sysroot
> >> > directory.
> >> > 3. The ext-toolchain-wrapper seems to point to the old (import-from)
> bin
> >> > directory, not the path to which the toolchain has been copied.
> >> >
> >> > I'm not particularly familiar with the relocatability of toolchains or
> >> > buildroot's method thereof, and so am not sure where to start with a
> >> > proposal, let alone a patch. If I could get some direction as to how
> >> > best to
> >> > tackle this, I'd be grateful.
> >>
> >> It is known that the toolchains generated by buildroot are not
> >> relocatable.
> >> However, you can tell buildroot to create the toolchain with
> >> crosstool-ng, and this one is relocatable. I suggest you give that a
> >> try to see if it solves your problems.
> >> I'm using buildroot in the same way and it works fine for me.
> >>
> >> Best regards,
> >> Thomas
> >
> >
>
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