Re: [PATCH] qemu-user: fix build with LLVM lld 10

["Alex Bennée" <alex.bennee@linaro.org>]

Roger Pau Monné <roger.pau@citrix.com> writes:

> On Fri, Mar 27, 2020 at 11:28:04AM +0000, Alex Bennée wrote:
>> 
>> Roger Pau Monné <roger.pau@citrix.com> writes:
>> 
>> > On Thu, Mar 26, 2020 at 09:56:38AM -0700, Richard Henderson wrote:
>> >> On 3/26/20 6:43 AM, Roger Pau Monne wrote:
>> >> > lld 10.0.0 introduced a new linker option --image-base equivalent to
>> >> > the GNU -Ttext-segment one, hence use it when available.
>> >> > 
>> >> > This fixes the build of QEMU on systems using lld 10 or greater.
>> >> > 
>> >> > Signed-off-by: Dimitry Andric <dim@FreeBSD.org>
>> >> > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
>> >> > ---
>> >> > Cc: Laurent Vivier <laurent@vivier.eu>
>> >> > Cc: Richard Henderson <richard.henderson@linaro.org>
>> >> > Cc: "Philippe Mathieu-Daudé" <philmd@redhat.com>
>> >> > Cc: Paolo Bonzini <pbonzini@redhat.com>
>> >> > Cc: "Daniel P. Berrangé" <berrange@redhat.com>
>> >> > ---
>> >> 
>> >> The Plan is still to drop this whole section of code.
>> >> 
>> >> However, it's still blocked on getting the x86_64 vsyscall patches upstream.
>> >
>> > While this doesn't materialize, could it be possible to get this patch
>> > accepted?
>> >
>> > This is currently blocking the build of QEMU on FreeBSD HEAD, which
>> > has already switched to LLVM 10.0.0.
>> 
>> I think the vsyscall patch has just been merged, however way I don't
>> think targeting HEAD of a OS release during the rc phase is appropriate.
>
> I'm not sure I understand what you mean. If QEMU doesn't build on
> FreeBSD HEAD it won't build on the next release. Also the LLVM
> toolchain used is not a development version AFAIK, but the actual
> 10.0.0 release, which QEMU should aim to support?

QEMU's supported build platforms are based on what is currently shipping
as stable versions:

  https://www.qemu.org/docs/master/system/build-platforms.html

> Can this be applied to stable branches then please if QEMU master
> doesn't have that chunk in configure anymore?

Usually platforms released after a given QEMU release will just carry
their own patches in the local packaging. When is the current HEAD due
to be cut as the next release? The schedule for QEMU's release is
documented on out planning pages:

  https://wiki.qemu.org/Planning/5.0

> FWIW, I've just looked at configure from git master branch and it
> still has that exact same linker detection chunk that this patch is
> trying to fix.

Now the vsyscalls patch is in this can be cleaned up I think. Richard?

-- 
Alex Bennée