From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Brown Subject: Re: [REGRESSION] "efi: efistub: Convert into static library" and preparation patches Date: Thu, 04 Sep 2014 13:54:09 +0100 Message-ID: <540860F1.6060801@fensystems.co.uk> References: <5405E186.2080406@canonical.com> <20140902192941.GB3001@console-pimps.org> <5406D0DB.90401@canonical.com> <54073409.6030004@canonical.com> <20140903175948.GH3001@console-pimps.org> <54084376.8090002@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <54084376.8090002-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Maarten Lankhorst , Ard Biesheuvel , Matt Fleming Cc: Ulf Winkelvos , Matt Fleming , LKML , "x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "H. Peter Anvin" , "linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Seth Forshee , Matthew Garrett List-Id: linux-efi@vger.kernel.org On 04/09/14 11:48, Maarten Lankhorst wrote: >>> If not, Ard please go ahead with option #2 above. Overkill yes, but I've >>> done the single __attribute__() hacks in other projects and someone >>> (usually me) always eventually forgets to tag some instance. >>> >> It appears we just got lucky on arm64, since we don't have any global >> variables, but the issue does exist there as well. >> > FWIW, visibility pushing doesn't seem to work for functions declared with extern. > Following seems to get rid of all GOTPCREL: Are you sure? The iPXE build process relies on this: /* Force visibility of all symbols to "hidden", i.e. inform gcc that * all symbol references resolve strictly within our final binary. * This avoids unnecessary PLT/GOT entries on x86_64. * * This is a stronger claim than specifying "-fvisibility=hidden", * since it also affects symbols marked with "extern". */ #ifndef ASSEMBLY #if __GNUC__ >= 4 #pragma GCC visibility push(hidden) #endif #endif /* ASSEMBLY */ and https://gcc.gnu.org/wiki/Visibility states that "#pragma GCC visibility is stronger than -fvisibility; it affects extern declarations as well. -fvisibility only affects definitions, so that existing code can be recompiled with minimal changes. This is more true for C than C++; C++ interfaces tend use classes, which are affected by -fvisibility." Michael