[U-Boot] U-Boot as first bootloader on Exynos platforms

[Paul Kocialkowski]

Hi,

Le mardi 01 mars 2016 à 06:27 -0700, Simon Glass a écrit :
> On 1 March 2016 at 01:10, Paul Kocialkowski <contact at paulk.fr> wrote:
> > Hi,
> > Le lundi 29 février 2016 à 19:03 -0700, Simon Glass a écrit :
> > > On 29 February 2016 at 03:15, Lukasz Majewski <l.majewski at samsung.com>
> > > wrote:
> > > > > I was told some time ago that a publicly-available version of the
> > > > > Samsung Chromebook 2 (supposedly, the one with an Exynos 5800 SoC)
> > > > > allows running unsigned code (the U-Boot SPL) directly after the
> > > > > bootrom. Is that correct?
> > > > > 
> > > > > Do you know of any (other) publicly available device with an Exynos
> > > > > SoC that doesn't check for the first bootloader's signature, and thus
> > > > > could load the U- Boot SPL without any intermediary signed stage on
> > > > > storage memory?
> > > > 
> > > > For sure Odroid XU3 needs signed SPL to boot up, so this devel board
> > > > will not work for you.
> > > 
> > > You can use snow which is Chromebook 1, or pit / pi which are
> > > Chromebook 2. I have not tried its 'BL1' with Odroid XU3 but I doubt
> > > it will work.
> > 
> > I know those have U-Boot support, but do any of them work without the
> > proprietary and signed on-memory first stage bootloaders?
> > 
> > I was told that at least snow's bootrom checks the signature of the first
> > bootloader it loads from memory. Is it the case for all Exynos devices?
> 
> I think that is true for all. But in the case of these Chromebooks,
> the BL1 does not check the signature of the image it loads, which
> breaks the chain. For Chrome OS, this kind of restriction is not
> useful, since the user should be able to run their own software on the
> platform. I'm really not sure why XU3 cannot do this too.

Thanks for the clarification!

-- 
Paul Kocialkowski, low-level free software developer on embedded devices

Website: https://www.paulk.fr/
Coding blog: https://code.paulk.fr/
Git repositories: https://git.paulk.fr/ https://git.code.paulk.fr/
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