linux-kernel - [tip: x86/urgent] x86/purgatory: Don't generate debug info for purgatory.ro

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Date:   Thu, 06 Aug 2020 17:10:04 -0000
From:   "tip-bot2 for Pingfan Liu" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Pingfan Liu <kernelfans@...il.com>, Ingo Molnar <mingo@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Steve Wahl <steve.wahl@....com>,
        Dave Young <dyoung@...hat.com>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/urgent] x86/purgatory: Don't generate debug info for purgatory.ro

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     b031cf7752a82fefa6818a788d906d14f533afa9
Gitweb:        https://git.kernel.org/tip/b031cf7752a82fefa6818a788d906d14f533afa9
Author:        Pingfan Liu <kernelfans@...il.com>
AuthorDate:    Mon, 03 Aug 2020 13:49:48 +08:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Thu, 06 Aug 2020 15:29:25 +02:00

x86/purgatory: Don't generate debug info for purgatory.ro

Purgatory.ro is a standalone binary that is not linked against the rest of
the kernel.  Its image is copied into an array that is linked to the
kernel, and from there kexec relocates it wherever it desires.

Unlike the debug info for vmlinux, which can be used for analyzing crash
such info is useless in purgatory.ro. And discarding them can save about
200K space.

 Original:
   259080  kexec-purgatory.o
 Stripped debug info:
    29152  kexec-purgatory.o

Signed-off-by: Pingfan Liu <kernelfans@...il.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Reviewed-by: Steve Wahl <steve.wahl@....com>
Acked-by: Dave Young <dyoung@...hat.com>
Link: https://lore.kernel.org/r/1596433788-3784-1-git-send-email-kernelfans@gmail.com
---
 arch/x86/purgatory/Makefile | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 088bd76..d24b43a 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -32,7 +32,7 @@ KCOV_INSTRUMENT := n
 # make up the standalone purgatory.ro
 
 PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
-PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss
+PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss -g0
 PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
 PURGATORY_CFLAGS += $(call cc-option,-fno-stack-protector)
 
@@ -64,6 +64,9 @@ CFLAGS_sha256.o			+= $(PURGATORY_CFLAGS)
 CFLAGS_REMOVE_string.o		+= $(PURGATORY_CFLAGS_REMOVE)
 CFLAGS_string.o			+= $(PURGATORY_CFLAGS)
 
+AFLAGS_REMOVE_setup-x86_$(BITS).o	+= -Wa,-gdwarf-2
+AFLAGS_REMOVE_entry64.o			+= -Wa,-gdwarf-2
+
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
 		$(call if_changed,ld)