ARM 17.0 profile migration with CHOST change

Title: ARM 17.0 profile migration with CHOST change
Author: James Le Cuirot <>
Content-Type: text/plain
Posted: 2018-09-07
Revision: 2
News-Item-Format: 1.0
Display-If-Keyword: arm
Display-If-Keyword: arm-linux

The new 17.0 profiles for ARM are now officially available. This not
only features the PIE migration previously announced for other
architectures but also a tuple (CHOST) change for hardfloat systems.

In short, the tuple will change from armv7a-hardfloat-linux-gnueabi to
armv7a-unknown-linux-gnueabihf or similar. This is to fall in line with
what the rest of the Linux community are now using. If the vendor (2nd)
part of your tuple is different or missing then you may keep it as it
is. The hf ending is what matters.

If you are using an unversioned alternative profile such as
hardened/linux/arm/armv7a then the default CHOST will have changed for
you already. Hopefully, you were shielded from the change by having
CHOST explicitly set in your make.conf. In this case, a migration is
still required.

Changing CHOST is never simple and does carry some risk. We encourage
users to migrate but if you do not have sys-devel/llvm on your system
and you do not cross-compile for ARM then you may choose to keep your
existing CHOST. We will continue to support this to some degree
although we cannot promise that other packages will not be affected in

If you choose not to migrate or your system is not hardfloat then you
must ensure that CHOST is explicitly set in make.conf and then proceed
with a regular 17.0 migration to deal with PIE as detailed here:

Otherwise, if you do wish to migrate then we have written a script to
do the necessary steps for you.

Download the raw script here:

View with syntax highlighting and change history here:

It takes a minimal backup of the existing toolchain with quickpkg
before changing anything but we strongly recommend that you take a
full backup first. The script echos each command as it goes along so
that you can keep an eye on what it's doing. You are, of course,
welcome to tinker with the script or perform the migration manually if
you think you know your own system better. It is heavily commented for
this reason.

If the script fails then you can take remedial action before running
it again and it should skip any time-consuming builds that it has
already done. If the migration doesn't go to plan then please do seek
help in #gentoo-arm.

A migration of this kind can justify rebuilding @world but with ARM
typically being very slow, the script does just the minimum
necessary. You are free to rebuild @world yourself after running it.