From mboxrd@z Thu Jan  1 00:00:00 1970
References: <79e94bdb-b97c-6f65-c3e7-1a62793855e9@siemens.com>
From: Philippe Gerum <rpm@xenomai.org>
Subject: Re: Arm userland not building with gcc-9 and later
In-reply-to: <79e94bdb-b97c-6f65-c3e7-1a62793855e9@siemens.com>
Date: Fri, 06 Aug 2021 15:09:21 +0200
Message-ID: <874kc267pa.fsf@xenomai.org>
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Xenomai <xenomai@xenomai.org>, Greg Gallagher <greg@embeddedgreg.com>


Jan Kiszka <jan.kiszka@siemens.com> writes:

> Hi all,
>
> just wanted to debug the RTnet issues we now see in CI on arm and arm64.
> I picked arm as first target, but that apparently starts to break with
> gcc-9 or newer (tried 9.2 and 10.2):
>
> make[5]: Entering directory '/xenomai/lib/cobalt/arch/arm'
>   CC       libarch_la-features.lo
> features.c: In function 'cobalt_arch_check_features':
> features.c:82:1: error: r7 cannot be used in 'asm' here
>    82 | }
>       | ^
>
> That seems to be related to passing the syscall number via r7 on ARM. Is
> our ABI soon no longer compilable, or can we fix this?
>
> Jan

r7 may be used as a scratch register by gcc in some
cases. -fomit-frame-pointer for debug builds may help (i.e. when the
optimizer is switched off).

-- 
Philippe.