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From: Paul Burton <paul.burton@imgtec.com>
To: <linux-mips@linux-mips.org>
Cc: Ralf Baechle <ralf@linux-mips.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Paul Burton <paul.burton@imgtec.com>
Subject: [PATCH 6/6] MIPS: Use thin archives & dead code elimination
Date: Thu, 20 Oct 2016 21:27:05 +0100	[thread overview]
Message-ID: <20161020202705.3783-7-paul.burton@imgtec.com> (raw)
In-Reply-To: <20161020202705.3783-1-paul.burton@imgtec.com>

Enable CONFIG_THIN_ARCHIVES & CONFIG_LD_DEAD_CODE_DATA_ELIMINATION for
MIPS, ensuring that we keep the data bus exception table & the machine
list which would be discarded without marking them with KEEP.

This shrinks a typical generic kernel build with drivers enabled for
Boston, Ci40 & SEAD-3 by around 5%, or ~450kb. As reported by
bloat-o-meter:

  add/remove: 0/3028 grow/shrink: 1/14 up/down: 18/-457362 (-457344)
  ...
  Total: Before=9001030, After=8543686, chg -5.08%

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Nicholas Piggin <npiggin@gmail.com>

---

 arch/mips/Kconfig              | 2 ++
 arch/mips/kernel/vmlinux.lds.S | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b3c5bde..8557667 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -66,6 +66,8 @@ config MIPS
 	select HAVE_EXIT_THREAD
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_ARCH_HARDENED_USERCOPY
+	select THIN_ARCHIVES
+	select LD_DEAD_CODE_DATA_ELIMINATION
 
 menu "Machine selection"
 
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index d1f5401..a43ba2a 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -72,7 +72,7 @@ SECTIONS
 	/* Exception table for data bus errors */
 	__dbe_table : {
 		__start___dbe_table = .;
-		*(__dbe_table)
+		KEEP(*(__dbe_table))
 		__stop___dbe_table = .;
 	}
 
@@ -122,7 +122,7 @@ SECTIONS
 	. = ALIGN(4);
 	.mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) {
 		__mips_machines_start = .;
-		*(.mips.machines.init)
+		KEEP(*(.mips.machines.init))
 		__mips_machines_end = .;
 	}
 
-- 
2.10.0

WARNING: multiple messages have this Message-ID (diff)
From: Paul Burton <paul.burton@imgtec.com>
To: linux-mips@linux-mips.org
Cc: Ralf Baechle <ralf@linux-mips.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Paul Burton <paul.burton@imgtec.com>
Subject: [PATCH 6/6] MIPS: Use thin archives & dead code elimination
Date: Thu, 20 Oct 2016 21:27:05 +0100	[thread overview]
Message-ID: <20161020202705.3783-7-paul.burton@imgtec.com> (raw)
Message-ID: <20161020202705.QaUVgwAGaymIsYrIsyCjJO7_fI0Qg5SkBef2qVgziT0@z> (raw)
In-Reply-To: <20161020202705.3783-1-paul.burton@imgtec.com>

Enable CONFIG_THIN_ARCHIVES & CONFIG_LD_DEAD_CODE_DATA_ELIMINATION for
MIPS, ensuring that we keep the data bus exception table & the machine
list which would be discarded without marking them with KEEP.

This shrinks a typical generic kernel build with drivers enabled for
Boston, Ci40 & SEAD-3 by around 5%, or ~450kb. As reported by
bloat-o-meter:

  add/remove: 0/3028 grow/shrink: 1/14 up/down: 18/-457362 (-457344)
  ...
  Total: Before=9001030, After=8543686, chg -5.08%

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Nicholas Piggin <npiggin@gmail.com>

---

 arch/mips/Kconfig              | 2 ++
 arch/mips/kernel/vmlinux.lds.S | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b3c5bde..8557667 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -66,6 +66,8 @@ config MIPS
 	select HAVE_EXIT_THREAD
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_ARCH_HARDENED_USERCOPY
+	select THIN_ARCHIVES
+	select LD_DEAD_CODE_DATA_ELIMINATION
 
 menu "Machine selection"
 
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index d1f5401..a43ba2a 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -72,7 +72,7 @@ SECTIONS
 	/* Exception table for data bus errors */
 	__dbe_table : {
 		__start___dbe_table = .;
-		*(__dbe_table)
+		KEEP(*(__dbe_table))
 		__stop___dbe_table = .;
 	}
 
@@ -122,7 +122,7 @@ SECTIONS
 	. = ALIGN(4);
 	.mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) {
 		__mips_machines_start = .;
-		*(.mips.machines.init)
+		KEEP(*(.mips.machines.init))
 		__mips_machines_end = .;
 	}
 
-- 
2.10.0

  parent reply	other threads:[~2016-10-20 20:30 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-20 20:26 [PATCH 0/6] MIPS: Use thin archives & dead code elimination Paul Burton
2016-10-20 20:26 ` Paul Burton
2016-10-20 20:27 ` [PATCH 1/6] kbuild: Keep device tree tables though " Paul Burton
2016-10-20 20:27   ` Paul Burton
2016-10-21  9:33   ` Sergei Shtylyov
2016-10-20 20:27 ` [PATCH 2/6] kbuild: Keep .init.setup section through " Paul Burton
2016-10-20 20:27   ` Paul Burton
2016-10-20 20:27 ` [PATCH 3/6] kbuild: Keep PCI fixups " Paul Burton
2016-10-20 20:27   ` Paul Burton
2016-10-20 20:27 ` [PATCH 4/6] kbuild: Keep earlycon table " Paul Burton
2016-10-20 20:27   ` Paul Burton
2016-10-20 20:27 ` [PATCH 5/6] MIPS: Ensure bss section ends on a long-aligned address Paul Burton
2016-10-20 20:27   ` Paul Burton
2016-11-04  8:46   ` Marcin Nowakowski
2016-11-04  8:46     ` Marcin Nowakowski
2016-10-20 20:27 ` Paul Burton [this message]
2016-10-20 20:27   ` [PATCH 6/6] MIPS: Use thin archives & dead code elimination Paul Burton
2016-10-21  0:51 ` [PATCH 0/6] " Nicholas Piggin
2016-10-21  0:51   ` Nicholas Piggin
2016-10-21  7:45   ` Paul Burton
2016-10-21  7:45     ` Paul Burton
2016-10-21  8:47     ` Nicholas Piggin
2016-10-21  8:47       ` Nicholas Piggin

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