On 2020-07-10, Kevin O'Connor wrote:
On Fri, Jul 10, 2020 at 11:58:06AM +0100, Nick Clifton wrote:
Hi Guys,
I have just updated PR 26047 with a suggested patch which I think could
resolve
this situation. (Patch attached here as well in order to save time). It adds
a new linker command line option: -z allowexec which will disable the
warnings
about linking in executable files. The default is still to have these
warnings
as I think that in most cases this behaviour makes sense.
Will this solve the problem for you ?
Hi Nick,
Thanks for looking at this.
I think the main issue is going to be the breaking of existing
software builds. In particular, as distros pull in the new version of
binutils, they'll run into errors building their current version of
SeaBIOS. Even if we update SeaBIOS today, it will be some time before
the distros will pull that change in. It'll also be a problem for
those trying to build older versions of SeaBIOS on newer toolchains.
Unless I'm missing something, this will also be a problem for those
building recent versions of the Linux kernel. It's build used this
ability of ld up until a few months ago (see
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=90ceddcb495008ac8ba7a3dce297841efcd7d584
). Although the latest Linux has changed, building older versions is
fairly common.
There is no problem (reject linking ET_EXEC as input) for 5.4, 5.6 and
HEAD. The fixes are in stable trees.
[PATCH 5.4 007/134] bpf: Support llvm-objcopy for vmlinux BTF
[PATCH 5.6 012/161] bpf: Support llvm-objcopy for vmlinux BTF
I haven't tested 5.2 (the first major release with potentially
problematic BTF commit) but if someone worries about 5.2 linkability
with GNU ld 2.35, the error can be downgraded to a warning.
It's unclear to me if there are other common packages
that use this ability of ld.
I don't think so. There is no FreeBSD package which has been marked
LLD_UNSAFE for the sole reason that older GNU ld accepts ET_EXEC while
LLD rejects ET_EXEC.
Among the tens of thousands of ports,
% rg -l LLD_UNSAFE
75
In the future there may be more ET_* types. I don't think linking them
will be correct/intended
https://groups.google.com/forum/#!topic/generic-abi/tJq7anc6WKs "RFC:
Add ET_DEBUG"
(the RFC has not been accepted but OSes can freely use ET_GNU_* )
The opinion in my other message
(https://sourceware.org/pipermail/binutils/2020-July/112283.html )
stands. allowexec will not be a suitable option name.
For seabios and Linux 5.2 (this major release only), a linker warning
should not hurt.
In a future release of GNU ld, the warning can be upgraded to an error.
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