From: Segher Boessenkool <segher@kernel.crashing.org> To: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: linuxppc-dev@lists.ozlabs.org, Paul Mackerras <paulus@samba.org>, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/vdso32: Add missing _restgpr_31_x to fix build failure Date: Thu, 11 Mar 2021 20:29:40 -0600 [thread overview] Message-ID: <20210312022940.GO29191@gate.crashing.org> (raw) In-Reply-To: <a7aa198a88bcd33c6e35e99f70f86c7b7f2f9440.1615270757.git.christophe.leroy@csgroup.eu> Hi! On Tue, Mar 09, 2021 at 06:19:30AM +0000, Christophe Leroy wrote: > With some defconfig including CONFIG_CC_OPTIMIZE_FOR_SIZE, > (for instance mvme5100_defconfig and ps3_defconfig), gcc 5 > generates a call to _restgpr_31_x. > I don't know if there is a way to tell GCC not to emit that call, because at the end we get more instructions than needed. The function is required by the ABI, you need to have it. You get *fewer* insns statically, and that is what -Os is about: reduce the size of the binaries. (The only reason you get such problems is because Linux does not have all of libgcc. You can have that *and* have some symbols cause link errors, it isn't rocket science). Segher
WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org> To: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] powerpc/vdso32: Add missing _restgpr_31_x to fix build failure Date: Thu, 11 Mar 2021 20:29:40 -0600 [thread overview] Message-ID: <20210312022940.GO29191@gate.crashing.org> (raw) In-Reply-To: <a7aa198a88bcd33c6e35e99f70f86c7b7f2f9440.1615270757.git.christophe.leroy@csgroup.eu> Hi! On Tue, Mar 09, 2021 at 06:19:30AM +0000, Christophe Leroy wrote: > With some defconfig including CONFIG_CC_OPTIMIZE_FOR_SIZE, > (for instance mvme5100_defconfig and ps3_defconfig), gcc 5 > generates a call to _restgpr_31_x. > I don't know if there is a way to tell GCC not to emit that call, because at the end we get more instructions than needed. The function is required by the ABI, you need to have it. You get *fewer* insns statically, and that is what -Os is about: reduce the size of the binaries. (The only reason you get such problems is because Linux does not have all of libgcc. You can have that *and* have some symbols cause link errors, it isn't rocket science). Segher
next prev parent reply other threads:[~2021-03-12 2:32 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-09 6:19 [PATCH] powerpc/vdso32: Add missing _restgpr_31_x to fix build failure Christophe Leroy 2021-03-09 6:19 ` Christophe Leroy 2021-03-12 2:29 ` Segher Boessenkool [this message] 2021-03-12 2:29 ` Segher Boessenkool 2021-03-15 16:23 ` Rasmus Villemoes 2021-03-15 16:23 ` Rasmus Villemoes 2021-03-15 16:38 ` David Laight 2021-03-15 16:38 ` David Laight 2021-03-15 23:59 ` Segher Boessenkool 2021-03-15 23:59 ` Segher Boessenkool 2021-03-16 9:35 ` David Laight 2021-03-16 9:35 ` David Laight 2021-03-15 23:47 ` Segher Boessenkool 2021-03-15 23:47 ` Segher Boessenkool 2021-03-12 13:09 ` Christophe Leroy 2021-03-15 13:31 ` Michael Ellerman 2021-03-15 13:31 ` Michael Ellerman
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