[Buildroot] Patch: new board Socrates Cyclone 5

[Lionel Flandrin]

On Tue, Aug 01, 2017 at 10:53:03AM +0200, Thomas Petazzoni wrote:
> Hello,
> 
> On Tue, 1 Aug 2017 09:54:56 +0200, Lionel Flandrin wrote:
> 
> > Can I access this preloader.bin somewhere? I could check if there's
> > anything obviously special about it.
> 
> The preloader.bin is part of the patch that Michał sent:
> 
>   https://patchwork.ozlabs.org/patch/795350/

Ah, I missed that, thank you for pointing it out.

It's definitely a mkpimage file. A simple way to validate that is to
check offset 0x40:

@0x40: [41 53 30 31]     Magic ("AS01")
@0x44: [00]              Version (v0 for Cyclone V)
@0x45: [00]              Flags
@0x46: [48 25]           Program length in words, so 38176B
@0x48: [00 00]           Not used ("spare")
@0x4a: [62 01]           Header checksum

Then at the end of the file you have a 4 byte CRC which I haven't
bothered to validate.

So nothing out of the ordinary as far as I can tell. In particular I
can't see anything ressembling a cryptographic signature at the
beginning or end of the file. Looks like a regular u-boot SPL to me.

I can't really say more about it, I don't have a Cyclone V board at
the moment. My advice would be to validate that the SPL generated by
u-boot does contain a valid mkpimage header. Since there are no
standard extensions (Altera uses ".bin" for everything) it's easy to
use the wrong file by mistake. I think buildroot's file should end in
".crc" (the ".bin" generated by u-boot is the raw u-boot binary and
can't be used as-is).

There's also the possibility of an error during flashing (truncated
file or something similar). If the mkpimage CRC is invalid the ROM
will bail out. So make sure you give the correct file size to your
flasher.

If everything else fails it should be possible to debug the boot
sequence with the JTAG, see if the CPU jumps into the SPL code at some
point. If it does then clearly it's the SPL that's bogus, otherwise
it's the boot ROM refusing to load it for some reason.

Here are some docs regarding "bare metal" debugging:
https://rocketboards.org/foswiki/view/Documentation/UsingDS5HeadlessDebuggerWithAlteraSoCs

> And the very reason why I opened up this thread is because it's not
> great to have pre-built bootloader images in the Buildroot tree.

I agree completely.

> Best regards,
> 
> Thomas

-- 
Lionel Flandrin
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