On Thu, Dec 4, 2014 at 3:41 PM, Alexander Graf <ag...@suse.de> wrote: > > > On 04.12.14 22:15, Olof Johansson wrote: >> On Thu, Dec 4, 2014 at 7:46 AM, Alexander Graf <ag...@suse.de> wrote: >>> With binutils 2.25 the default alignment for 32bit arm sections changed to >>> have everything 64k aligned. Armv7 binaries built with this binutils version >>> run successfully on an arm64 system. >>> >>> Since effectively there is now the chance to run armv7 code on arm64 even >>> with 64k page size, it doesn't make sense to block people from enabling >>> CONFIG_COMPAT on those configurations. >>> >>> Signed-off-by: Alexander Graf <ag...@suse.de> >>> --- >>> arch/arm64/Kconfig | 1 - >>> 1 file changed, 1 deletion(-) >>> >>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >>> index 9532f8d..3cf4f238 100644 >>> --- a/arch/arm64/Kconfig >>> +++ b/arch/arm64/Kconfig >>> @@ -409,7 +409,6 @@ source "fs/Kconfig.binfmt" >>> >>> config COMPAT >>> bool "Kernel support for 32-bit EL0" >>> - depends on !ARM64_64K_PAGES >>> select COMPAT_BINFMT_ELF >>> select HAVE_UID16 >>> select OLD_SIGSUSPEND3 >> >> This is hardly "compat". Sure, it's great to have a new binutils that >> has larger alignment, but practically not a single existing binary >> will work today if someone tries to do this. > > Yes, but IMHO that's an implementation detail. The same applies for > 32bit PPC binaries if you use 4k aligned segments. If your applications > are not aligned for your page size, you can't run them. The only > platform that managed nevertheless FWIW was IA64 ;).
Yes, but there the binutils change happened early enough that by the time the kernel change went in, all major distros had binaries that were compatible. >> So, it seems very premature to take this off. At the very least >> document it like Will requested, and make it depend on !ARM_64K_PAGES >> || EXPERT. > > Sure, that certainly works for me (though you probably mean Laura). Yeah, sorry Laura. :) > Completely restricting users from enabling it just because our current > toolchain doesn't generate compatible binaries sounds a bit extreme to me. Perhaps. It's in many ways a timing thing too, if ARM had patched binutils a couple of years ago it might have been fine to just go with it without EXPERT now. :) -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
