[U-Boot] [PATCH v2] arm64: allow space reservation for boot header

[Steve Rae]

On Wed, May 25, 2016 at 9:50 AM, Andre Przywara <andre.przywara at arm.com>
wrote:

> Hi,
>
> On 25/05/16 17:15, Steve Rae wrote:
> > Hi,
> >
> > On Wed, May 25, 2016 at 1:48 AM, Hans de Goede <hdegoede at redhat.com
> > <mailto:hdegoede at redhat.com>> wrote:
> >
> >     Hi,
> >
> >     On 25-05-16 10:40, Andre Przywara wrote:
> >
> >         Some SPL loaders (like Allwinner's boot0) require a header
> >         before the
> >         actual U-Boot binary to both check its validity and to find
> >         other data
> >         to load.
> >         Introduce a config option to reserve some space at the beginning
> >         of the
> >         binary to later hold the header if needed.
> >         Please note that the current arm64 start.S jumps over some
> >         portion of
> >         data already, so this option bascially just increases this region
> >         to allow post-processing tools to insert more data there.
> >         This also means that both filling the header is optional and
> >         also having
> >         some extra space in there does not hurt apart from enlarging the
> >         binary.
> >
> >         For the use with Allwinner's boot0 blob there is a tool called
> >         boot0img[1], which fills the header to allow booting A64 based
> >         boards.
> >         For the Pine64 we need a 1536 Byte header (including the branch
> >         instruction) at the moment, so we add this to the defconfig.
> >
> >         Signed-off-by: Andre Przywara <andre.przywara at arm.com
> >         <mailto:andre.przywara at arm.com>>
> >
> >         [1] https://github.com/apritzel/pine64/tree/master/tools
> >
> >
> >     v2 looks good to me:
> >
> >     Acked-by: Hans de Goede <hdegoede at redhat.com
> >     <mailto:hdegoede at redhat.com>>
> >
> >     Tom, can you pick this one up please (I'm asking you since it is
> >     touching some non sunxi files) ?
> >
> >     Regards,
> >
> >     Hans
> >
> >
> >
> >         ---
> >          arch/arm/cpu/armv8/start.S    | 3 +++
> >          board/sunxi/Kconfig           | 7 +++++++
> >          configs/pine64_plus_defconfig | 1 +
> >          include/configs/sun50i.h      | 4 ++++
> >          4 files changed, 15 insertions(+)
> >
> >         diff --git a/arch/arm/cpu/armv8/start.S
> b/arch/arm/cpu/armv8/start.S
> >         index e933021..a9cd7e9 100644
> >         --- a/arch/arm/cpu/armv8/start.S
> >         +++ b/arch/arm/cpu/armv8/start.S
> >         @@ -21,6 +21,9 @@
> >          _start:
> >                 b       reset
> >
> >         +#ifdef CONFIG_START_HEADER_SPACE
> >         +       .space CONFIG_START_HEADER_SPACE /* can be filled with a
> >         boot0 header */
> >         +#endif
> >                 .align 3
> >
> >
> > Just wondering, is there any way to make this even more generic?
> > In your case, you are wanting
> >         .space 1532
> > But in my case I am actually wanting something like:
> >         .word   0x12345678
> >         .word   _end - _start
> > Thanks, Steve
>
> I don't think we should go down that rabbit hole. Mainline U-Boot just
> provides the space for it, and you have a post-processing tool that
> fills it. This is what we do for Allwinner's boot0 (which includes
> magics, checksums, sizes, load address, etc.) You could even include
> this tool in the build process, similar to mkimage calls.
>
> Or if you like, feel free to send a patch which shows how you imagine that.
>
> Cheers,
> Andre.
>
>
I agree that this _might_ be a rabbit hole, but the following is fairly
straightforward and seems to work:

+#ifdef CONFIG_BOOT0_CODE
+CONFIG_BOOT0_CODE
+#endif

( then elsewhere: )
+#define CONFIG_BOOT0_CODE      \
+       .word  0x12345678;     \
+       .word   _end - _start

And for your code:
+#define CONFIG_BOOT0_CODE      \
+       .space  1532

The "hint" is that these lines need to start with a tab, and need the
semi-colon to separate lines....
Would this work for you?
Thanks Steve

>
> >          .globl _TEXT_BASE
> >         diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
> >         index fa78720..9f2e17e 100644
> >         --- a/board/sunxi/Kconfig
> >         +++ b/board/sunxi/Kconfig
> >         @@ -15,6 +15,13 @@ config SUNXI_GEN_SUN6I
> >                 separate ahb reset control registers, custom pmic bus,
> >         new style
> >                 watchdog, etc.
> >
> >         +config SUNXI_BOOT0
> >         +       bool "prepare for boot0 header"
> >         +       ---help---
> >         +       If U-Boot is loaded from the Allwinner provided boot0
> >         blob, it
> >         +       expects a header area filled with magic values.
> >         +       This option will add some space at the beginning of the
> >         image to
> >         +       let a tool later on fill in this header with sensible
> data.
> >
> >          choice
> >                 prompt "Sunxi SoC Variant"
> >         diff --git a/configs/pine64_plus_defconfig
> >         b/configs/pine64_plus_defconfig
> >         index 0977334..b93e4da 100644
> >         --- a/configs/pine64_plus_defconfig
> >         +++ b/configs/pine64_plus_defconfig
> >         @@ -18,3 +18,4 @@ CONFIG_CMD_EXT2=y
> >          CONFIG_CMD_EXT4=y
> >          CONFIG_CMD_FAT=y
> >          CONFIG_CMD_FS_GENERIC=y
> >         +CONFIG_SUNXI_BOOT0=y
> >         diff --git a/include/configs/sun50i.h b/include/configs/sun50i.h
> >         index 0fdb4c7..6923b60 100644
> >         --- a/include/configs/sun50i.h
> >         +++ b/include/configs/sun50i.h
> >         @@ -17,6 +17,10 @@
> >          #define GICD_BASE              0x1c81000
> >          #define GICC_BASE              0x1c82000
> >
> >         +#ifdef CONFIG_SUNXI_BOOT0
> >         +#define CONFIG_START_HEADER_SPACE      1532
> >         +#endif
> >         +
> >          /*
> >           * Include common sunxi configuration where most the settings
> are
> >           */
> >
> >
>