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Peter Anvin" , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH] x86, build: remove -m16 workaround for unsupported versions of GCC Message-ID: <20201201035146.GA1469908@ubuntu-m3-large-x86> References: <20201201011307.3676986-1-ndesaulniers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201201011307.3676986-1-ndesaulniers@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 30, 2020 at 05:13:06PM -0800, 'Nick Desaulniers' via Clang Built Linux wrote: > A revert of the following two commits. > commit de3accdaec88 ("x86, build: Build 16-bit code with -m16 where > possible") > commit a9cfccee6604 ("x86, build: Change code16gcc.h from a C header to > an assembly header") > > Since commit 0bddd227f3dc ("Documentation: update for gcc 4.9 > requirement") the minimum supported version of GCC is gcc-4.9. It's now > safe to remove this code. > > Signed-off-by: Nick Desaulniers Reviewed-by: Nathan Chancellor > --- > arch/x86/Makefile | 9 +-------- > arch/x86/boot/code16gcc.h | 12 ------------ > 2 files changed, 1 insertion(+), 20 deletions(-) > delete mode 100644 arch/x86/boot/code16gcc.h > > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index 1bf21746f4ce..7116da3980be 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -24,14 +24,7 @@ endif > > # How to compile the 16-bit code. Note we always compile for -march=i386; > # that way we can complain to the user if the CPU is insufficient. > -# > -# The -m16 option is supported by GCC >= 4.9 and clang >= 3.5. For > -# older versions of GCC, include an *assembly* header to make sure that > -# gcc doesn't play any games behind our back. > -CODE16GCC_CFLAGS := -m32 -Wa,$(srctree)/arch/x86/boot/code16gcc.h > -M16_CFLAGS := $(call cc-option, -m16, $(CODE16GCC_CFLAGS)) > - > -REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING \ > +REALMODE_CFLAGS := -m16 -g -Os -DDISABLE_BRANCH_PROFILING \ > -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \ > -fno-strict-aliasing -fomit-frame-pointer -fno-pic \ > -mno-mmx -mno-sse > diff --git a/arch/x86/boot/code16gcc.h b/arch/x86/boot/code16gcc.h > deleted file mode 100644 > index e19fd7536307..000000000000 > --- a/arch/x86/boot/code16gcc.h > +++ /dev/null > @@ -1,12 +0,0 @@ > -/* SPDX-License-Identifier: GPL-2.0 */ > -# > -# code16gcc.h > -# > -# This file is added to the assembler via -Wa when compiling 16-bit C code. > -# This is done this way instead via asm() to make sure gcc does not reorder > -# things around us. > -# > -# gcc 4.9+ has a real -m16 option so we can drop this hack long term. > -# > - > - .code16gcc > -- > 2.29.2.454.gaff20da3a2-goog >