From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=66.187.233.73; helo=mx1.redhat.com; envelope-from=lersek@redhat.com; receiver=edk2-devel@lists.01.org Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 69E24203B8CD4 for ; Tue, 22 May 2018 02:05:25 -0700 (PDT) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DD4DD4201AE7; Tue, 22 May 2018 09:05:24 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-120-18.rdu2.redhat.com [10.10.120.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id C5B22112129D; Tue, 22 May 2018 09:05:20 +0000 (UTC) To: Ard Biesheuvel , "Gao, Liming" Cc: edk2-devel-01 , "Danilo C. L. de Paula" , Cole Robinson , Gerd Hoffmann , Leif Lindholm , Paolo Bonzini , "Zhu, Yonghong" References: <20180518182301.25265-1-lersek@redhat.com> <4A89E2EF3DFEDB4C8BFDE51014F606A14E22C7AD@SHSMSX104.ccr.corp.intel.com> From: Laszlo Ersek Message-ID: <1e8c24de-2ed7-b328-61b4-df85db46b22d@redhat.com> Date: Tue, 22 May 2018 11:05:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Tue, 22 May 2018 09:05:24 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Tue, 22 May 2018 09:05:24 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'lersek@redhat.com' RCPT:'' Subject: Re: [PATCH] BaseTools/tools_def: add "-fno-unwind-tables" to GCC_AARCH64_CC_FLAGS X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 May 2018 09:05:26 -0000 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 05/21/18 11:32, Ard Biesheuvel wrote: > On 21 May 2018 at 02:37, Gao, Liming wrote: >> Laszlo: >> Is this change required for IA32 and X64 arch? >> > > The upstream GCC change is limited to AArch64, but I suppose it > wouldn't hurt to add this to IA32/X64 as well, given that it currently > only reaffirms the default, and will do the right thing if that > default ever changes for IA32/X64 as well. Right; I wanted to keep the patch surgical. I don't really understand why it makes sense for gcc to use different "unwind-tables" defaults for AARCH64 vs. IA32/X64; however, I did think the gcc developers must have made a conscious decision, to restrict the change to AARCH64. I can submit a followup patch for IA32/X64, but I'll first respond under Leif's suggestion too (that subthread will likely take more discussion). Thanks! Laszlo > > >>> -----Original Message----- >>> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org] >>> Sent: Saturday, May 19, 2018 4:21 PM >>> To: Laszlo Ersek >>> Cc: edk2-devel-01 ; Danilo C. L. de Paula ; Cole Robinson ; >>> Gerd Hoffmann ; Leif Lindholm ; Gao, Liming ; Paolo Bonzini >>> ; Zhu, Yonghong >>> Subject: Re: [PATCH] BaseTools/tools_def: add "-fno-unwind-tables" to GCC_AARCH64_CC_FLAGS >>> >>> On 18 May 2018 at 20:23, Laszlo Ersek wrote: >>>> The ElfConvert routines in GenFw don't handle the ".eh_frame" ELF section >>>> emitted by gcc. For this reason, Leif disabled the generation of that >>>> section for AARCH64 with "-fno-asynchronous-unwind-tables" in commit >>>> 28e80befa4fe [1], and Ard did the same for IA32 and X64 in commit >>>> 26ecc55c027d [2]. (The CLANG38 toolchain received the same flag at its >>>> inception, in commit 6f756db5ea05 [3].) >>>> >>>> However, ".eh_frame" is back now; in upstream gcc commit 9cbee213b579 [4] >>>> (part of tag "gcc-8_1_0-release"), both "-fasynchronous-unwind-tables" and >>>> "-funwind-tables" were made the default for AARCH64. (The patch author >>>> described the effects on the gcc mailing list [5].) We have to counter the >>>> latter flag with "-fno-unwind-tables", otherwise GenFw chokes on >>>> ".eh_frame" again (triggered for example on Fedora 28). >>>> >>>> "-f[no-]unwind-tables" goes back to at least gcc-4.4 [6], so it's safe to >>>> add to GCC_AARCH64_CC_FLAGS. >>>> >>>> [1] https://github.com/tianocore/edk2/commit/28e80befa4fe >>>> [2] https://github.com/tianocore/edk2/commit/26ecc55c027d >>>> [3] https://github.com/tianocore/edk2/commit/6f756db5ea05 >>>> [4] https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=9cbee213b579 >>>> [5] http://mid.mail-archive.com/7b28c03a-c032-6cec-c127-1c12cbe98eeb@foss.arm.com >>>> [6] https://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Code-Gen-Options.html >>>> >>>> Cc: "Danilo C. L. de Paula" >>>> Cc: Ard Biesheuvel >>>> Cc: Cole Robinson >>>> Cc: Gerd Hoffmann >>>> Cc: Leif Lindholm >>>> Cc: Liming Gao >>>> Cc: Paolo Bonzini >>>> Cc: Yonghong Zhu >>>> Reported-by: "Danilo C. L. de Paula" >>>> Contributed-under: TianoCore Contribution Agreement 1.1 >>>> Signed-off-by: Laszlo Ersek >>> >>> Reviewed-by: Ard Biesheuvel >>> >>>> --- >>>> >>>> Notes: >>>> Repo: https://github.com/lersek/edk2.git >>>> Branch: aarch64_no_unwind_tables >>>> >>>> BaseTools/Conf/tools_def.template | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template >>>> index 03d700018550..9429033fe2e3 100755 >>>> --- a/BaseTools/Conf/tools_def.template >>>> +++ b/BaseTools/Conf/tools_def.template >>>> @@ -4537,7 +4537,7 @@ DEFINE GCC_X64_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -mno-red-zone -Wno-ad >>>> DEFINE GCC_IPF_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -minline-int-divide-min-latency >>>> DEFINE GCC_ARM_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -mlittle-endian -mabi=aapcs -fno-short-enums >>> -funsigned-char -ffunction-sections -fdata-sections -fomit-frame-pointer -Wno-address -mthumb -mfloat-abi=soft -fno-pic -fno-pie >>>> DEFINE GCC_ARM_CC_XIPFLAGS = -mno-unaligned-access >>>> -DEFINE GCC_AARCH64_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -mlittle-endian -fno-short-enums -fverbose-asm >>> -funsigned-char -ffunction-sections -fdata-sections -Wno-address -fno-asynchronous-unwind-tables -fno-pic -fno-pie -ffixed-x18 >>>> +DEFINE GCC_AARCH64_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -mlittle-endian -fno-short-enums -fverbose-asm >>> -funsigned-char -ffunction-sections -fdata-sections -Wno-address -fno-asynchronous-unwind-tables -fno-unwind-tables -fno-pic >>> -fno-pie -ffixed-x18 >>>> DEFINE GCC_AARCH64_CC_XIPFLAGS = -mstrict-align -mgeneral-regs-only >>>> DEFINE GCC_DLINK_FLAGS_COMMON = -nostdlib --pie >>>> DEFINE GCC_DLINK2_FLAGS_COMMON = -Wl,--script=$(EDK_TOOLS_PATH)/Scripts/GccBase.lds >>>> -- >>>> 2.14.1.3.gb7cf6e02401b >>>>