[PATCH 1/2] ARM: Add Kconfig option to use mkimage -T kernel_noload

[Marek Vasut]

Dear Jean-Christophe PLAGNIOL-VILLARD,

> On 10:33 Wed 29 Feb     , Tim Bird wrote:
> > On 02/29/2012 10:14 AM, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > > On 08:58 Wed 29 Feb     , Stephen Warren wrote:
> > >> Jean-Christophe PLAGNIOL-VILLARD wrote at Wednesday, February 29, 2012 
5:30 AM:
> > >>> On 17:03 Tue 28 Feb     , Stephen Warren wrote:
> > >>>> uImage files typically encode a single absolute load and entry
> > >>>> address. This is inconvenient when attempting to share that uImage
> > >>>> across multiple SoCs with different physical RAM addresses. Recent
> > >>>> versions of mkimage implement a "kernel_noload" image type which
> > >>>> encodes no absolute load address, and a relative entry address.
> > >>>> This works well for uImage-wrapped ARM zImages, since they are
> > >>>> relocatable.
> > >>>> 
> > >>>> This is enabled by commit b9b50e89d317c58becd0e2d7fac2e21e3a81dd0a
> > >>>> "image: Implement IH_TYPE_KERNEL_NOLOAD" in U-Boot.
> > >>>> 
> > >>>> Signed-off-by: Stephen Warren <swarren at nvidia.com>
> > >>>> ---
> > >>>> I assume I should put this into the ARM patch tracker if it's OK?
> > >>> 
> > >>> Again a new option for uImage no why not just boot the zImage
> > >>> 
> > >>> in this case the uImage is useless
> > >> 
> > >> U-Boot doesn't support zImage at present.
> > >> 
> > >> A patch was posted to support it at least for ARM, but needed a little
> > >> work before it could be committed.
> > > 
> > > Sorry I see no advantage to have the uImage build by the kernel anymore
> > > as we have a relocatable zImage
> > > 
> > > I'll even drop its support
> > 
> > This seems at least premature, and possibly ill-advised in general.
> > There are lots of U-Boot images out in the field, many of which that
> > are rarely updated. A lot of workflow will be disrupted unnecessarily
> > by a change like this.
> > 
> > Could you wait to drop uImage build support in the kernel until
> > U-Boot supports zImage, and has worked it's way into the field
> > for a few years?
> 
> I'm fine to keep for now on but not to add new feature
> 
> Barebox (former U-Boot v2) support zImage for quite a while and
> relocable one for too.

On the other hand, noone uses barebox and you should stop with this obvious 
malice towards uboot please. I believe for most people it's easier to spend time 
only on implementing their hardware support into U-Boot, not waste time 
implementing basic components that are still missing in barebox.

Last but not least, the uImage contains additional checksum on the whole image, 
which is useful on flash media.

That said, I'm all for having uImage support in kernel and for adding this 
NOLOAD option.

Best regards,
Marek Vasut