[Dev] Unfortunate things about Odroid XU support.

Marek Szyprowski m.szyprowski at samsung.com
Tue Sep 16 09:18:35 GMT 2014


Hello,

On 2014-09-16 10:09, Heecheol, Yang wrote:
>
> Hello,
>
> I am personally trying to port Tizen on my odroidXU board which has 
> Exynos 5410 SoC.
>
> Struggling for about 3 months, I concluded that it is almost 
> impossible now due to several reasons below, and I am considering to 
> give up porting work.
>
> However, I thought that I’d better to share my experiences before I 
> really decide to give up. So, I am writing this mail to share what I 
> have suffered from.
>
> First of all, I want to mention that the stable Linux kernel version 
> which OdroidXU supports is 3.4. It is the first barrier that makes me 
> impossible to port.
>
> As you know, Tizen’s security framework is based on underlying SMACK 
> in kernel. However, kernel 3.4 doesn’t have adequate version of SMACK.
>
> To be specific, when I booted Tizen on that kernel version, booting 
> failed because systemd failed to access load2 interface in smackfs.
>
> Actually, LOAD2 interface is supported from kernel >= 3.10. When I 
> realized the fact, I tried to find higher kernel version that supports 
> Odroid XU.
>
> Fortunately, I found 3.13 and 3.14 kernel version from link below.
>
> https://github.com/hardkernel/linux/tree/odroid-3.13.y-linaro
>
> It was experimental and non-stable version and It was originally 
> intended to support Ubuntu. Of course, It works well when I booted 
> this version with Ubuntu.
>
> However, when I tried to boot the kernel with Tizen rootfs, the 
> booting stopped printing ‘imprecise external abort’. The error is very 
> similar to the link below.
>
> http://lists.infradead.org/pipermail/linux-arm-kernel/2013-November/214882.html
>
> At first, I thought that the error may be related to the Tizen, not 
> kernel. However I changed my thought, and implicitly concluded that it 
> may be related to kernel. But not exactly.
>
> Anyway, whatever the error is related to, it was so hard to debug for me.
>

This might be the same issue we had with Odroid U3/X2 boards. The secure 
firmware, which is used on those boards protects the last 64k of system 
memory for its internal use. Make sure that you limited the total amount 
of memory to 2GiB-64k instead of passing whole 2GiB (this is done 
automatically by the reference v3.4 kernel).

> In summary
>
> 1.Stable Odroid XU kernel version(3.4) can’t support Tizen due to old 
> SMACK version.
>
> 2.The experimental version of recent kernel version has a bug 
> difficult to solve.
>
> These are what I experienced and followings are what I think have to 
> do if I would continue porting work.
>
> 1.Backport up-to-date version of SMACK into the stable kernel 3.4 or
>
> 2.Solve the problems in kernel 3.13
>

The third option would be to add support for Exynos 5410/5420 to v3.10 
kernel on tizen.org, but this is still quite a lot of work. The good 
thing is that Exynos4/5 related stuff in v3.10 kernel on tizen.org is 
more or less compatible with the code merged to mainline kernels.

Please also note that Exynos 5410 has different GPU module (SGI PVR) 
than other Exynos SoCs (ARM MALI), what will also require changes to 
userspace gfx stack.

> Yes, they are possible to do but as a premature person, it is very 
> difficult for me to do alone. I have no debugging hardware tools, not 
> enough knowledge, and so on. This is the most important reason: I am 
> premature.
>
> So I want to conclude my mail by saying thanks to many people who 
> helped in various ways.
>
> In someday, I wish to port Tizen on my board.
>
>

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland



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