[RFC] Add a LOADADDR= option when building uImage

From: Julien Boibessot <julien.boibessot@armadeus.com>

This seems mandatory in recent Linux kernels configured with ARCH_MULTIPLATFORM
(well at least on ARM/i.MX).
If LOADADDR variable is not set when building multi-arch uImage then a dummy
loadaddr is used, that prevent this image to boot in U-Boot (2012.04 in my
case).
Anyone else who need the same fix ?

Signed-off-by: Julien Boibessot <julien.boibessot@armadeus.com>
---
 linux/Config.in |    8 ++++++++
 linux/linux.mk  |    4 ++++
 2 files changed, 12 insertions(+), 0 deletions(-)

Julien,

I would appreciate this patch because I spent a lot of time
discovering LOADADDR and this would have really helped me.  My
suggestions:

1) Should this variable be exposed only for ARM for now?  ("depends on
BR2_arm || BR2_armeb")

2) Should this variable only be exposed for linux versions >= 3.7?
3.7 is when CONFIG_ARCH_MULTIPLATFORM appears.

3) The description in the help text might not help someone new to this
topic (like me).  I would suggest something like:

"If your ARM system's kernel is configured via the new (3.7+)
multi-architecture support (CONFIG_ARCH_MULTIPLATFORM=y in your linux
kernel .config), then it is necessary to specify a kernel load address
for the uImage.  This should be a hexadecimal string beginning with
0x.  Example setting: 0x00008000."

Thanks and best of luck,

       -dp


On Mon, Mar 11, 2013 at 3:35 AM,  <julien.boibessot@free.fr> wrote:
> From: Julien Boibessot <julien.boibessot@armadeus.com>
>
> This seems mandatory in recent Linux kernels configured with ARCH_MULTIPLATFORM
> (well at least on ARM/i.MX).
> If LOADADDR variable is not set when building multi-arch uImage then a dummy
> loadaddr is used, that prevent this image to boot in U-Boot (2012.04 in my
> case).
> Anyone else who need the same fix ?
>
> Signed-off-by: Julien Boibessot <julien.boibessot@armadeus.com>
> ---
>  linux/Config.in |    8 ++++++++
>  linux/linux.mk  |    4 ++++
>  2 files changed, 12 insertions(+), 0 deletions(-)
>
> diff --git a/linux/Config.in b/linux/Config.in
> index 94ce951..c582439 100644
> --- a/linux/Config.in
> +++ b/linux/Config.in
> @@ -213,6 +213,14 @@ config BR2_LINUX_KERNEL_IMAGE_TARGET_NAME
>           Specify the kernel make target to build the kernel that you
>           need.
>
> +config BR2_LINUX_KERNEL_UIMAGE_LOADADDR
> +       string "loadaddr for uImage"
> +       depends on BR2_LINUX_KERNEL_UIMAGE || BR2_LINUX_KERNEL_APPENDED_UIMAGE
> +       help
> +         When configured for multi-arch support, it is mandatory to define
> +         LOADADDR=0x... when asking recent kernels to generate a uImage.
> +         Let this option empty if your kernel is single-arch only.
> +
>  config BR2_LINUX_KERNEL_DTS_SUPPORT
>         bool "Device tree support"
>         help
> diff --git a/linux/linux.mk b/linux/linux.mk
> index 0352acd..361ce3c 100644
> --- a/linux/linux.mk
> +++ b/linux/linux.mk
> @@ -95,6 +95,10 @@ LINUX_IMAGE_NAME=vmlinuz
>  endif
>  endif
>
> +ifeq ($(LINUX_IMAGE_NAME),uImage)
> +LINUX_MAKE_FLAGS+=LOADADDR=$(call qstrip,$(BR2_LINUX_KERNEL_UIMAGE_LOADADDR))
> +endif
> +
>  ifeq ($(BR2_LINUX_KERNEL_APPENDED_DTB),y)
>  LINUX_IMAGE_TARGET=zImage
>  else
> --
> 1.7.5.4
>
> _______________________________________________
> buildroot mailing list
> buildroot@busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot



--
Daniel.Price@gmail.com; Twitter: @danielbprice

Hello Daniel,

On 03/12/2013 09:39 AM, Daniel Price wrote:
> Julien,
>
> I would appreciate this patch because I spent a lot of time
> discovering LOADADDR and this would have really helped me.  My
> suggestions:

thanks for your feedback !

> 1) Should this variable be exposed only for ARM for now?  ("depends on
> BR2_arm || BR2_armeb")

yes, I will do

> 2) Should this variable only be exposed for linux versions >= 3.7?
> 3.7 is when CONFIG_ARCH_MULTIPLATFORM appears.

yes, but I don't know how to do that.
any idea ?

> 3) The description in the help text might not help someone new to this
> topic (like me).  I would suggest something like:
>
> "If your ARM system's kernel is configured via the new (3.7+)
> multi-architecture support (CONFIG_ARCH_MULTIPLATFORM=y in your linux
> kernel .config), then it is necessary to specify a kernel load address
> for the uImage.  This should be a hexadecimal string beginning with
> 0x.  Example setting: 0x00008000."

yes that's better than mine.
I'm just trying to figure out how to depend from
CONFIG_ARCH_MULTIPLATFORM and then I will send a new version of my patch.

Thanks !

Regards,
Julien

On 03/12/13 21:44, Julien Boibessot wrote:
> Hello Daniel,
>
> On 03/12/2013 09:39 AM, Daniel Price wrote:
>> Julien,
[snip]
>> 2) Should this variable only be exposed for linux versions >= 3.7?
>> 3.7 is when CONFIG_ARCH_MULTIPLATFORM appears.
>
> yes, but I don't know how to do that.
> any idea ?

  That's not currently possible in buildroot. It's impossible to derive 
that automatically at configure time.


>> 3) The description in the help text might not help someone new to this
>> topic (like me).  I would suggest something like:
>>
>> "If your ARM system's kernel is configured via the new (3.7+)
>> multi-architecture support (CONFIG_ARCH_MULTIPLATFORM=y in your linux
>> kernel .config), then it is necessary to specify a kernel load address
>> for the uImage.  This should be a hexadecimal string beginning with
>> 0x.  Example setting: 0x00008000."
>
> yes that's better than mine.
> I'm just trying to figure out how to depend from
> CONFIG_ARCH_MULTIPLATFORM and then I will send a new version of my patch.

  Also not possible, because the kernel configuration is separate from 
the buildroot configuration.


  Having an extensive help text is generally considered sufficient.

  Perhaps the prompt could be a bit more explicit still, e.g. "load 
address (for multi-platform image)" (note that the reference to U-Boot is 
redundant since it's already a dependency).

  Regards,
  Arnout