Hello Albert,
Am 11.06.2014 09:14, schrieb Albert ARIBAUD:
Hi Masahiro,
(to: the board maintainers for enbw_cmc, da850evm_direct_nor, and
calimain)
On Mon, 09 Jun 2014 18:29:26 +0900, Masahiro Yamada
<[email protected]> wrote:
Hi Albert,
You changed the behaviour of three boards,
"enbw_cmc", "da850evm_direct_nor", "calimain"!
Probably they are broken.
These boards expects "0x00000011" (=CONFIG_SYS_DV_NOR_BOOT_CFG)
at the beginning of the image.
But since commit 41623c91, that is missing.
If you still don't understand, you should checkout 41623c91^ and
41623c91 and compare u-boot.dis.
Your description of the effects of my change is correct. However, this
raises another question which I would like to see discussed before
doing anything about these boards.
Taking the last commit where the prefix word was actually emitted (that
is, 41623c91^, which is actually 60a4f39f, "arm: remove unused _end_vect
and _vectors_end symbols"), and reading arch/arm/cpu/arm926ejs/start.S,
I see that the start of the image looks like this:
offset Content
+0x0000 prefix word CONFIG_SYS_DV_NOR_BOOT_CFG
+0x0004 reset vector
+0x0008 undefined instruction vector
+0x000c software interrupt vector
+0x0010 prefetch abort vector
+0x0014 data abort vector
+0x0018 unused
+0x001c irq vector
+0x0020 fiq vector
+0x0024 (end of vectors table)
And that is /wrong/: the vectors table is misaligned by 4 bytes.
Obviously, the boards have been working fine for a long time, because
no exception vector was used apparently (or because when exceptions did
happen, the error was debugged without the need to analyze the
exception).
I suspect we could just remove the '.word CONFIG_SYS_DV_NOR_BOOT_CFG'
line from the vectors.S file and prepend the word to the image /after/
linking.
This, of course, requires confirmation from maintainers.
Manfred, Christian, Sudhakar, Heiko: can any one of you let us know the
reason for this signature word exactly, and how exactly it is used by
the board? Ideally, can you also:
See "AM18xx Bootloader Application Report":
http://www.ti.com/lit/pdf/spraba5
Section "3.1 NOR Boot" on page 3ff
This word is used to setup some settings ...
- test a current build (which does not have the signature word) and
confirm it fails to load);
- test the same build with the 4-byte signature manually prepended
(this may possibly require padding the image);
I try to find some time for it ...
bye,
Heiko
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