Re: [PATCH 4/4] ti33x, ti43x, omap-a15: switch KERNEL_IMAGETYPE to zImage by default

[Tom Rini <trini@ti.com>]

On 09/24/2013 09:49 AM, Maupin, Chase wrote:
>> -----Original Message-----
>> From: meta-ti-bounces@yoctoproject.org [mailto:meta-ti-
>> bounces@yoctoproject.org] On Behalf Of Rini, Tom
>> Sent: Tuesday, September 24, 2013 8:01 AM
>> To: Dmytriyenko, Denys
>> Cc: meta-ti@yoctoproject.org
>> Subject: Re: [meta-ti] [PATCH 4/4] ti33x, ti43x, omap-a15: switch
>> KERNEL_IMAGETYPE to zImage by default
>>
>> On 09/24/2013 12:39 AM, Denys Dmytriyenko wrote:
>>> On Tue, Sep 24, 2013 at 03:36:47AM +0000, Cooper Jr., Franklin
>> wrote:
>>>> What is the benefit of this switch?
>>>>
>>>> Although outdated a lot of posts talking about uImage vs zImage
>> seems to
>>>> favor uImage due to additional functionality that it provides.
>>>
>>> I guess this is a more generic question addressed to Tom...
>>
>> There are two sides to it.  On the zImage side, it's what the
>> kernel
>> produces normally, without needing other tools, so it's vastly
>> preferred
>> by the majority of kernel developers.  On the production side,
>> uImages
>> provide useful things like a checksums and the ability to detect
>> overlaps.  If we enabled FIT images, we could go so far as to
>> allow for
>> cryptographically signed images and configurations (what FIT calls
>> a
>> kernel+fdt(+optional ramdisk)).
>>
>> For community oriented things like this, zImage is best and for
>> production, it's up to the designer on what's important and what's
>> not.
> 
> A key point is that either can still be used with new u-boots.  Tom,
> I think you were saying there is a way if the AMSDK wants to for it
> to fall back to uImage if zImage is not found.

Right, so we can have more complex boot logic than we do today, coming
in from uEnv.txt even if we want, rather than patching.  To have a
complex (and thus fragile) "try everything":
fallbackload=\
if load $loadaddr 0 uImage; then run mmcloados;fi \
if load $loadaddr $bootpart $bootdir/$bootfile; then ... copy/paste
mmcloados logic, but with bootz not boot; fi
uenvcmd=run fallbackload

-- 
Tom