Standalone API examples on the P4080DS

Hi all,

I have compiled the hello_world standalone API example documented at
http://www.denx.de/wiki/view/DULG/UBootStandalone for the Freescale P4080DS development board.

For the standalone api example hello_world, the tutorial (linked above) states that the entry point of the application *is offset 4 bytes from the start of the file* (I.E. address 0x40004).

With all build settings at default, my standalone base address is 0x40000 (defined in arch/powerpc/config.mk). This produces the following object code:

00040000 <hello_world>:

    40000:	94 21 ff e0 	stwu    r1,-32(r1)
    40004:	7c 08 02 a6 	mflr    r0
    40008:	bf 61 00 0c 	stmw    r27,12(r1)
    4000c:	7c 7e 1b 78 	mr      r30,r3
    40010:	7c 83 23 78 	mr      r3,r4
    40014:	90 01 00 24 	stw     r0,36(r1)

It looks like the entry point is 0x40000. Why does the tutorial state that the example needs to be run from a 4 byte offset? In this case this will result in a failure to create a stack frame for hello_world.

Thanks!

Dave George

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Hi David,

For PowerPC the entry point used to be non-deterministic, but was generally 0x40004 which is where the wiki value came from. The following 2 patches made the entry point consistently 0x40000:

http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=commit;h=620bbba524fbaa26971a5004793010b169824f1b

http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=commit;h=c91d456c055237bdadb99a80e198748b8cf32595

I updated the wiki to match the newer 0x40000 address, which is valid for PowerPC boards with a comment to check out CONFIG_STANDALONE_LOAD_ADDR for other architectures.

Peter

Thank you very much for this Peter, it's much appreciated, and should hopefully stop anyone else falling into the same trap!

Thanks!

Dave George

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