diff mbox

[U-Boot,v2] mpc85xx/u-boot*.lds: remove _GLOBAL_OFFSET_TABLE_ definition

Message ID 1445749348-22106-1-git-send-email-prabhakar@freescale.com
State Accepted
Delegated to: Tom Rini
Headers show

Commit Message

Prabhakar Kushwaha Oct. 25, 2015, 5:02 a.m. UTC 
From: Zhenhua Luo <zhenhua.luo@freescale.com>

In binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbols defined by PROVIDE in
u-boot.lds overrides the linker built-in symbols
(https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;
h=b893397a4b1316610f49819344817715e4305de9),
so the linker is treating _GLOBAL_OFFSET_TABLE_ as a definition into the
.reloc section.

To align with the change of binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbol
should not be defined in sections, and the symbols in linker generated .got
section should be used(https://sourceware.org/ml/binutils/2008-09/
msg00122.html)

Fixed the following build errors with binutils-2.25:
| powerpc-poky-linux-gnuspe-ld.bfd: _GLOBAL_OFFSET_TABLE_ not defined in
linker created .got

Signed-off-by: Zhenhua Luo <zhenhua.luo@freescale.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
---
Changes for v2: Updated Subject

 arch/powerpc/cpu/mpc85xx/u-boot-nand.lds     | 1 -
 arch/powerpc/cpu/mpc85xx/u-boot-nand_spl.lds | 1 -
 arch/powerpc/cpu/mpc85xx/u-boot-spl.lds      | 1 -
 arch/powerpc/cpu/mpc85xx/u-boot.lds          | 1 -
 4 files changed, 4 deletions(-)

Comments

York Sun Oct. 30, 2015, 5:12 p.m. UTC | #1 
On 10/24/2015 10:02 PM, Prabhakar Kushwaha wrote:
> From: Zhenhua Luo <zhenhua.luo@freescale.com>
> 
> In binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbols defined by PROVIDE in
> u-boot.lds overrides the linker built-in symbols
> (https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;
> h=b893397a4b1316610f49819344817715e4305de9),
> so the linker is treating _GLOBAL_OFFSET_TABLE_ as a definition into the
> .reloc section.
> 
> To align with the change of binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbol
> should not be defined in sections, and the symbols in linker generated .got
> section should be used(https://sourceware.org/ml/binutils/2008-09/
> msg00122.html)
> 
> Fixed the following build errors with binutils-2.25:
> | powerpc-poky-linux-gnuspe-ld.bfd: _GLOBAL_OFFSET_TABLE_ not defined in
> linker created .got
> 
> Signed-off-by: Zhenhua Luo <zhenhua.luo@freescale.com>
> Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
> ---
> Changes for v2: Updated Subject
> 

Prabhakar/Zhenghua,

Have you addressed Tom's comment (on rev 1 patch)? Quote, "What happens when we
use older binutils?  I'd like some run-time testing too please".

York
Joakim Tjernlund Nov. 2, 2015, 4:17 p.m. UTC | #2 
On Fri, 2015-10-30 at 10:12 -0700, York Sun wrote:
> 
> On 10/24/2015 10:02 PM, Prabhakar Kushwaha wrote:
> > From: Zhenhua Luo <zhenhua.luo@freescale.com>
> > 
> > In binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbols defined by PROVIDE in
> > u-boot.lds overrides the linker built-in symbols
> > (https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;
> > h=b893397a4b1316610f49819344817715e4305de9),

hmm, what was the reson for this change in binutils? As I recall, PROVIDE should
only add a symbol when there is none and now binutils just ignores this, strange.

> > so the linker is treating _GLOBAL_OFFSET_TABLE_ as a definition into the
> > .reloc section.

Yes, where do you want it instead? what is the difference with/without PROVIDE?

> > 
> > To align with the change of binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbol
> > should not be defined in sections, and the symbols in linker generated .got
> > section should be used(https://sourceware.org/ml/binutils/2008-09/
> > msg00122.html)
> > Fixed the following build errors with binutils-2.25:
> > > powerpc-poky-linux-gnuspe-ld.bfd: _GLOBAL_OFFSET_TABLE_ not defined in
> > linker created .got
> > 
> > Signed-off-by: Zhenhua Luo <zhenhua.luo@freescale.com>
> > Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
> > ---
> > Changes for v2: Updated Subject
> > 
> 
> Prabhakar/Zhenghua,
> 
> Have you addressed Tom's comment (on rev 1 patch)? Quote, "What happens when we
> use older binutils?  I'd like some run-time testing too please".
> 
> York
> 
> _______________________________________________
> U-Boot mailing list
> U-Boot@lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot
Joakim Tjernlund Nov. 2, 2015, 6:48 p.m. UTC | #3 
[Resending with old email address]

I want to add why PROVIDE was added in the first place:
In theory it is possible to build an u-boot without ld defining
_GLOBAL_OFFSET_TABLE_, in that case we create _GLOBAL_OFFSET_TABLE_ ourself.

Should we start using -fPIC* one day this will we will be close to
an u-boot without _GLOBAL_OFFSET_TABLE_ and the __got2_entries calculation
will fail.

*older gcc's will automatically promote -fpic to -fPIC when used with -mrelocatable
 I wrote a small patch in 2010 to fix this:
 https://gcc.gnu.org/ml/gcc-patches/2010-10/msg02301.html
 Cannot remember what gcc version(4.6?) that went into.

About the same time support for -msingle-pic-base was added to powerpc gcc
This would reduce code size further, possibly interesting for SPL?
I sent som patches for that but there were something holding them
back.


On Mon, 2015-11-02 at 17:17 +0100, Joakim Tjernlund wrote:
> On Fri, 2015-10-30 at 10:12 -0700, York Sun wrote:
> > 
> > On 10/24/2015 10:02 PM, Prabhakar Kushwaha wrote:
> > > From: Zhenhua Luo <zhenhua.luo@freescale.com>
> > > 
> > > In binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbols defined by PROVIDE in
> > > u-boot.lds overrides the linker built-in symbols
> > > (https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;
> > > h=b893397a4b1316610f49819344817715e4305de9),
> 
> hmm, what was the reson for this change in binutils? As I recall, PROVIDE should
> only add a symbol when there is none and now binutils just ignores this, strange.
> 
> > > so the linker is treating _GLOBAL_OFFSET_TABLE_ as a definition into the
> > > .reloc section.
> 
> Yes, where do you want it instead? what is the difference with/without PROVIDE?
> 
> > > 
> > > To align with the change of binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbol
> > > should not be defined in sections, and the symbols in linker generated .got
> > > section should be used(https://sourceware.org/ml/binutils/2008-09/
> > > msg00122.html)
> > > Fixed the following build errors with binutils-2.25:
> > > > powerpc-poky-linux-gnuspe-ld.bfd: _GLOBAL_OFFSET_TABLE_ not defined in
> > > linker created .got
> > > 
> > > Signed-off-by: Zhenhua Luo <zhenhua.luo@freescale.com>
> > > Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
> > > ---
> > > Changes for v2: Updated Subject
> > > 
> > 
> > Prabhakar/Zhenghua,
> > 
> > Have you addressed Tom's comment (on rev 1 patch)? Quote, "What happens when we
> > use older binutils?  I'd like some run-time testing too please".
> > 
> > York
> > 
> > _______________________________________________
> > U-Boot mailing list
> > U-Boot@lists.denx.de
> > http://lists.denx.de/mailman/listinfo/u-boot
Tom Rini Nov. 10, 2015, 8:16 p.m. UTC | #4 
On Sun, Oct 25, 2015 at 10:32:28AM +0530, Prabhakar Kushwaha wrote:

> From: Zhenhua Luo <zhenhua.luo@freescale.com>
> 
> In binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbols defined by PROVIDE in
> u-boot.lds overrides the linker built-in symbols
> (https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;
> h=b893397a4b1316610f49819344817715e4305de9),
> so the linker is treating _GLOBAL_OFFSET_TABLE_ as a definition into the
> .reloc section.
> 
> To align with the change of binutils-2.25, the _GLOBAL_OFFSET_TABLE_ symbol
> should not be defined in sections, and the symbols in linker generated .got
> section should be used(https://sourceware.org/ml/binutils/2008-09/
> msg00122.html)
> 
> Fixed the following build errors with binutils-2.25:
> | powerpc-poky-linux-gnuspe-ld.bfd: _GLOBAL_OFFSET_TABLE_ not defined in
> linker created .got
> 
> Signed-off-by: Zhenhua Luo <zhenhua.luo@freescale.com>
> Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>

Applied to u-boot/master, thanks!
diff mbox

Patch

diff --git a/arch/powerpc/cpu/mpc85xx/u-boot-nand.lds b/arch/powerpc/cpu/mpc85xx/u-boot-nand.lds
index f933b21..0399f93 100644
--- a/arch/powerpc/cpu/mpc85xx/u-boot-nand.lds
+++ b/arch/powerpc/cpu/mpc85xx/u-boot-nand.lds
@@ -44,7 +44,6 @@  SECTIONS
     _GOT2_TABLE_ = .;
     KEEP(*(.got2))
     KEEP(*(.got))
-    PROVIDE(_GLOBAL_OFFSET_TABLE_ = . + 4);
     _FIXUP_TABLE_ = .;
     KEEP(*(.fixup))
   }
diff --git a/arch/powerpc/cpu/mpc85xx/u-boot-nand_spl.lds b/arch/powerpc/cpu/mpc85xx/u-boot-nand_spl.lds
index b83c553..f044564 100644
--- a/arch/powerpc/cpu/mpc85xx/u-boot-nand_spl.lds
+++ b/arch/powerpc/cpu/mpc85xx/u-boot-nand_spl.lds
@@ -22,7 +22,6 @@  SECTIONS
 		_GOT2_TABLE_ = .;
 		KEEP(*(.got2))
 		KEEP(*(.got))
-		PROVIDE(_GLOBAL_OFFSET_TABLE_ = . + 4);
 		_FIXUP_TABLE_ = .;
 		KEEP(*(.fixup))
 	}
diff --git a/arch/powerpc/cpu/mpc85xx/u-boot-spl.lds b/arch/powerpc/cpu/mpc85xx/u-boot-spl.lds
index 5ae7b3e..889a4c2 100644
--- a/arch/powerpc/cpu/mpc85xx/u-boot-spl.lds
+++ b/arch/powerpc/cpu/mpc85xx/u-boot-spl.lds
@@ -29,7 +29,6 @@  SECTIONS
 		_GOT2_TABLE_ = .;
 		KEEP(*(.got2))
 		KEEP(*(.got))
-		PROVIDE(_GLOBAL_OFFSET_TABLE_ = . + 4);
 		_FIXUP_TABLE_ = .;
 		KEEP(*(.fixup))
 	}
diff --git a/arch/powerpc/cpu/mpc85xx/u-boot.lds b/arch/powerpc/cpu/mpc85xx/u-boot.lds
index 2cf0b25..f15eaf3 100644
--- a/arch/powerpc/cpu/mpc85xx/u-boot.lds
+++ b/arch/powerpc/cpu/mpc85xx/u-boot.lds
@@ -50,7 +50,6 @@  SECTIONS
     _GOT2_TABLE_ = .;
     KEEP(*(.got2))
     KEEP(*(.got))
-    PROVIDE(_GLOBAL_OFFSET_TABLE_ = . + 4);
     _FIXUP_TABLE_ = .;
     KEEP(*(.fixup))
   }