97 lines
3.9 KiB
Diff
97 lines
3.9 KiB
Diff
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From b98275138bf4fc250a1c362dfd2c8b1cf2421701 Mon Sep 17 00:00:00 2001
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From: Michael Chang <mchang@suse.com>
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Date: Tue, 28 Sep 2021 13:50:47 +0800
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Subject: build: Fix build error with binutils 2.36
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The following procedure to build xen/pvgrub is broken.
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git clone https://git.savannah.gnu.org/git/grub.git
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cd grub
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./bootstrap
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mkdir build-xen
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cd build-xen
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../configure --with-platform=xen
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make
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It fails with the message:
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/usr/lib64/gcc/x86_64-suse-linux/10/../../../../x86_64-suse-linux/bin/ld:
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section .note.gnu.property VMA [0000000000400158,0000000000400187]
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overlaps section .bss VMA [000000000000f000,000000000041e1af]
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The most significant factor is that new assembler (GNU as) generates the
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.note.gnu.property section as default. This note section overlaps with
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.bss because it doesn't reposition with -Wl,-Ttext,0 with which the base
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address of .text section is set, rather the address of .note.gnu.property
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is calculated for some reason from 0x400000 where the ELF executable
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defaults to start.
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Using -Ttext-segment doesn't help either, though it is said to set the
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address of the first byte of the text segment according to "man ld".
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What it actually does is to override the default 0x400000, aka the image
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base address, to something else. The entire process can be observed in
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the default linker script used by gcc [1]. Therefore we can't expect it
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to achieve the same thing as -Ttext given that the first segment where
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.text resides is offset by SIZEOF_HEADERS plus some sections may be
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preceding it within the first segment. The end result is .text always
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has to start with non-zero address with -Wl,-Ttext-segment,0 if using
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default linker script.
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It is also worth mentioning that binutils upstream apparently doesn't
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seem to consider this as a bug [2] and proposed to use -Wl,-Ttext-segment,0
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which is not fruitful as what has been tested by Gentoo [3].
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As long as GRUB didn't use ISA information encoded in .note.gnu.property,
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we can safely drop it via -Wa,-mx86-used-note=no assembler option to
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fix the linker error above.
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This is considered a better approach than using custom linker script to
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drop the .note.gnu.property section because object file manipulation can
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also be hampered one way or the other in that linker script may not be
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helpful. See also this commit removing the section in the process of objcopy.
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6643507ce build: Fix GRUB i386-pc build with Ubuntu gcc
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[1] In /usr/lib64/ldscripts/elf_x86_64.x or use 'gcc -Wl,--verbose ...'
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PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x400000));
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. = SEGMENT_START("text-segment", 0x400000) + SIZEOF_HEADERS;
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[2] https://sourceware.org/bugzilla/show_bug.cgi?id=27377
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[3] https://bugs.gentoo.org/787221
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Signed-off-by: Michael Chang <mchang@suse.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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configure.ac | 14 ++++++++++++++
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1 file changed, 14 insertions(+)
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(limited to 'configure.ac')
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diff --git a/configure.ac b/configure.ac
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index eeb5d22..8d1c81a 100644
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--- a/configure.ac
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+++ b/configure.ac
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@@ -840,6 +840,20 @@ if ( test "x$target_cpu" = xi386 || test "x$target_cpu" = xx86_64 ) && test "x$p
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TARGET_CFLAGS="$TARGET_CFLAGS -mno-mmx -mno-sse -mno-sse2 -mno-sse3 -mno-3dnow"
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fi
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+if ( test "x$target_cpu" = xi386 || test "x$target_cpu" = xx86_64 ); then
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+ AC_CACHE_CHECK([whether -Wa,-mx86-used-note works], [grub_cv_cc_mx86_used_note], [
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+ CFLAGS="$TARGET_CFLAGS -Wa,-mx86-used-note=no -Werror"
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+ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
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+ [grub_cv_cc_mx86_used_note=yes],
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+ [grub_cv_cc_mx86_used_note=no])
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+ ])
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+
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+ if test "x$grub_cv_cc_mx86_used_note" = xyes; then
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+ TARGET_CFLAGS="$TARGET_CFLAGS -Wa,-mx86-used-note=no"
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+ TARGET_CCASFLAGS="$TARGET_CCASFLAGS -Wa,-mx86-used-note=no"
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+ fi
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+fi
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+
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# GRUB doesn't use float or doubles at all. Yet some toolchains may decide
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# that floats are a good fit to run instead of what's written in the code.
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# Given that floating point unit is disabled (if present to begin with)
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--
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cgit v1.1
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