Date: Mon, 10 Mar 2014 20:42:38 -0600 From: Warner Losh <imp@bsdimp.com> To: Andrew Turner <andrew@fubar.geek.nz> Cc: freebsd-arm@freebsd.org Subject: Re: Updating the minimum armv6 requirement Message-ID: <E19645D3-0297-4620-91F2-D394117F567C@bsdimp.com> In-Reply-To: <20140311131945.01f4c9b2@bender> References: <20140311131945.01f4c9b2@bender>
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On Mar 10, 2014, at 6:19 PM, Andrew Turner <andrew@fubar.geek.nz> wrote: > I've been looking at code that uses 64-bit C++ atomic operations on > armv6. These require the ldrexd and strexd instructions that are > present on armv6k. > > The problem is there is a mismatch between clang and binutils. Clang > thinks armv6k is an arm1136jf-s and sets the cpu in the asm output as > one. Binutils will see the cpu and think clang means an earlier armv6 > instruction set that lacks the above instructions. > > In this case both are correct as prior to the r1p0 release of the > arm1136jf-s core it was an armv6 core, and as of the r1p0 release it > became an armv6k core. > > All of this is uninteresting for FreeBSD as the only ARMv6 SoC we run > on appears to be the bcm2835, and maybe some Marvell parts. As the > bcm2835 is an arm1176jzf-s and we are unlikely to get a new ARMv6 port I > am suggesting we make this the minimum requirement. It appears NetBSD > has the same requirement as clang will set the cpu to arm1176jzf-s when > building for NetBSD and armv6. > > My proposal is to have the same CPU requirement as NetBSD for armv6. Is > anyone working on an SoC that would be affected by this? I think this is OK. Is there some way to make the new requirement a compile time error, or kernel-time panic? Warner
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