CONFIG_64BIT and CONFIG_BUILD_ELF64

CONFIG_64BIT and CONFIG_BUILD_ELF64

[Martin Michlmayr]

I'm trying to build a 64bit kernel for Cobalt and get the following.
Is there a good reason why CONFIG_64BIT does not activate
CONFIG_BUILD_ELF64 automatically?

  CC      init/main.o
Assembler messages:
Error: -mgp64 used with a 32-bit ABI
make[1]: *** [init/main.o] Error 1

-- 
Martin Michlmayr
http://www.cyrius.com/

Re: CONFIG_64BIT and CONFIG_BUILD_ELF64

[Maciej W. Rozycki]

On Wed, 18 Jan 2006, Martin Michlmayr wrote:

> Is there a good reason why CONFIG_64BIT does not activate
> CONFIG_BUILD_ELF64 automatically?

 It works with some old toolchains and apparently there are people who 
want this feature.  Please feel free to propose a patch to add such a 
dependency and see if there are any objections.

  Maciej

Re: CONFIG_64BIT and CONFIG_BUILD_ELF64

[Ralf Baechle]

On Wed, Jan 18, 2006 at 12:42:25PM +0000, Maciej W. Rozycki wrote:

> On Wed, 18 Jan 2006, Martin Michlmayr wrote:
> 
> > Is there a good reason why CONFIG_64BIT does not activate
> > CONFIG_BUILD_ELF64 automatically?
> 
>  It works with some old toolchains and apparently there are people who 
> want this feature.  Please feel free to propose a patch to add such a 
> dependency and see if there are any objections.

At this stage support for gcc 2.95 is decaying and soon may be removed
entirely from the kernel.  So the time to hardwire CONFIG_BUILD_ELF64=y
may have come.

  Ralf

Re: CONFIG_64BIT and CONFIG_BUILD_ELF64

[Martin Michlmayr]

* Ralf Baechle <ralf@linux-mips.org> [2006-01-18 12:51]:
> At this stage support for gcc 2.95 is decaying and soon may be removed
> entirely from the kernel.  So the time to hardwire CONFIG_BUILD_ELF64=y
> may have come.

[mips] Enable BUILD_ELF64 when 64BIT is set

New toolchain does not support building 32-bit ELF objects with 64-bit
code, so we enable BUILD_ELF64 when 64bit is on.

Ralf Baechle: "At this stage support for gcc 2.95 is decaying and soon
may be removed entirely from the kernel.  So the time to hardwire
CONFIG_BUILD_ELF64=y may have come."

Signed-off-by: Martin Michlmayr <tbm@cyrius.com>

---
 Kconfig |   12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

--- linux-mips/arch/mips/Kconfig	2006-01-10 11:21:15.000000000 +0000
+++ new/arch/mips/Kconfig	2006-01-18 14:07:15.000000000 +0000
@@ -1722,17 +1722,7 @@
 config BUILD_ELF64
 	bool "Use 64-bit ELF format for building"
 	depends on 64BIT
-	help
-	  A 64-bit kernel is usually built using the 64-bit ELF binary object
-	  format as it's one that allows arbitrary 64-bit constructs.  For
-	  kernels that are loaded within the KSEG compatibility segments the
-	  32-bit ELF format can optionally be used resulting in a somewhat
-	  smaller binary, but this option is not explicitly supported by the
-	  toolchain and since binutils 2.14 it does not even work at all.
-
-	  Say Y to use the 64-bit format or N to use the 32-bit one.
-
-	  If unsure say Y.
+	default y
 
 config BINFMT_IRIX
 	bool "Include IRIX binary compatibility"

-- 
Martin Michlmayr
http://www.cyrius.com/

Re: CONFIG_64BIT and CONFIG_BUILD_ELF64

[Stephen P. Becker]

Maciej W. Rozycki wrote:
> On Wed, 18 Jan 2006, Martin Michlmayr wrote:
> 
>> Is there a good reason why CONFIG_64BIT does not activate
>> CONFIG_BUILD_ELF64 automatically?
> 
>  It works with some old toolchains and apparently there are people who 
> want this feature.  Please feel free to propose a patch to add such a 
> dependency and see if there are any objections.
> 

Interesting this was brought up today, as Kumba and I were having a 
little discussion concerning this yesterday.  The thing is that for 
certain machines such as ip22 and ip32, booting a ELF64 kernel is 
problematic, so people have to make sure they use the vmlinux.32 target.

-Steve

Re: CONFIG_64BIT and CONFIG_BUILD_ELF64

[Maciej W. Rozycki]

On Wed, 18 Jan 2006, Stephen P. Becker wrote:

> discussion concerning this yesterday.  The thing is that for certain machines
> such as ip22 and ip32, booting a ELF64 kernel is problematic, so people have
> to make sure they use the vmlinux.32 target.

 Absolutely.  Making `make boot' build a reasonable bootable object for a 
given platform might not be a bad idea.

  Maciej