[U-Boot] Regarding learning reference of uboot loading secondary uboot

[Simon Glass]

Hi,

On 27 May 2015 at 21:41,  <pratapnaidu at gmail.com> wrote:
> Hi Simon,
>                 Thanks for of your time and quick replies.  The idea seems
> to be good, but still confused with the way to implement it. Please help me
> to give a final thought to solve this with the existing framework, sorry for
> my inexperience with u-boot, kindly enlighten with the following:
>
> 1) How to sign the primary and secondary u-boot image with the same key,
> after that  do i need to write a routine similar to  “bootm_find_os”  or
> “bootm_find_loadables" to find the secondary uboot image and load it into
> the memory,

If the first U-Boot is in read-only flash then it cannot be updated,
so does not need to be signed. If it is in read-write flash, then you
probably can't prevent it being overwritten. You could protect half of
the flash, perhaps, and put the read-only U-Boot in the proetced half.

Yes you can write a simple routine to load it.

> 2) can we have a dummy fit image with only secondary u-boot image within the
> .its file for the first u-boot loader

I don't understand this sorry.

> 3)Sorry to ask you this, do you have any  partial code i can follow and
> shred some light to carry on further.

I don't have anything that reads a read-write U-Boot and jumps to it,
other than the Chrome OS code that i think you have.

>
>
> I really thanks you to answer my all questions with patience,i would have
> not disturbed you, but because of project dead-line i was forced to be
> carried out with the situation.

OK. Please try to make the questions clear so that I can understand
what you are asking.

>
> Thanks,
> pratap
>

Regards,
Simon

>
>
>
>
>
>
> On May 23, 2015, at 2:12 PM, Simon Glass <sjg at chromium.org> wrote:
>
> Hi,
>
> On 23 May 2015 at 13:02, Maddimsetty Pratap <pratapnaidu at gmail.com> wrote:
>
> Hi Simon,
>              Thanks for you quick reply and sorry for the confusion over
> forum,here is my request for help
>
>             1)  Do you know any repository which had already did it
> "verify second u-boot signature" over beaglebone.
>
>
> I'm not sure if this was done or not. You could look in cros/amxx here:
>
> https://chromium.googlesource.com/chromiumos/third_party/u-boot/+/chromeos-v2013.06
>
> or a newer version that doesn't currently support beaglebone.
>
> https://chromium.googlesource.com/chromiumos/third_party/u-boot/+/chromeos-v2015.07-rc1
>
> The Chrome OS implementation uses the same crypto but has custom
> binary data structures. I'm working a bit on trying to bridge the gap
> but we are not there yet.
>
> So the easiest way to make this work is probably to use the FIT
> signature verification and put your second U-Boot into the FIT. That
> should handle the verification and then after it loads you can turn
> off the cache and jump to it. It already works on Beaglebone and the
> only difference is that it is currently set up to load a kernel, but
> you want to load U-Boot.
>
>
>             2) Please verify and confirm the following link, if i was going
> in the right direction.
>
> http://git.chromium.org/gitweb/?p=chromiumos/third_party/u-boot.git;a=commit;h=b9e8864294d8f2143ce17b4e0d4ba019b6348199
>
> Thanks,
> pratap
>
>
> Regards,
> Simon
>
>
> Thanks,
> pratap
>
> On Thu, May 21, 2015 at 6:32 PM, Simon Glass <sjg at chromium.org> wrote:
>
>
> Hi,
>
> It's here:
>
> https://chromium.googlesource.com/chromiumos/third_party/u-boot
>
> in branch chromeos-v2013.06. It is implemented for chromeos_peach.
>
> If you have further questions, please send them to the U-Boot mailing list
> and cc me.
>
> Regards,
> Simon
>
>
> On 21 May 2015 at 17:25, Maddimsetty Pratap <pratapnaidu at gmail.com> wrote:
>
>
> Hi Simon,
>               I am apologize to e-mail you directly. In one of your
> presentations regarding FIT, you had stated uboot loading a signed secondary
> uboot loader in chromium. I would be glad if you provide me with any
> reference regarding the same.
>
>
> Here is the statement from LWN.net.
>
>
> "Chrome OS starts up U-Boot, loads and verifies a second U-Boot, loads
> and verifies a kernel and jumps to it all in under 700ms on a modern SoC"
>
> Thanks,
> pratap
>
>
>
>
>
>
>
>
>
>
> --
> pratap naidu
>
>