[U-Boot] [PATCH 06/11] imx: imx-common: introduce boot auxiliary core

[Tom Rini]

On Thu, Jan 14, 2016 at 09:54:24AM -0800, Stefan Agner wrote:
> On 2016-01-14 09:15, Tom Rini wrote:
> > On Wed, Jan 13, 2016 at 12:45:05PM -0800, Stefan Agner wrote:
> >> Hi,
> >>
> >> I would like to keep the discussion going and shed some light on the
> >> image format introduced here, see below...
> >>
> >> On 2016-01-07 00:38, Peng Fan wrote:
> >> > Hi Stefan,
> >> > On Wed, Jan 06, 2016 at 10:59:17PM -0800, Stefan Agner wrote:
> >> >>On 2016-01-04 21:56, Peng Fan wrote:
> >> >>> From: Peng Fan <peng.fan at nxp.com>
> >> >>>
> >> >>> To boot a auxiliary core in asymmetric multicore system, introduce the
> >> >>> new command "bootaux" to do it. Example of boot auxliary core from
> >> >>> 0x70000000 where stores the boot head information that should be
> >> >>> parsed by auxiliary core, "bootaux 0x70000000".
> >> >>
> >> >>This reminds me of a question which was nagging me lately:
> >> >>Is the M4 core of SoloX/MX7 running a boot ROM? Or who/what is "parsing
> >> >>the boot head information"?
> >> >
> >> > There is no bootrom for m4 core. The bootimage for M4 contains stack
> >> > info and pc info. bootaux command will use the info extracted from bootimage.
> >>
> >>
> >> So the image expected by bootaux is really a raw binary image, with the
> >> only notion that the first two words need to be the stack pointer and
> >> the reset handler (firmware entry point).
> >>
> >> U-Boot has other commands which work with "raw" images, such as the
> >> bootz command. The bootz command also expects a certain "raw" format,
> >> hence I guess it is ok to introduce something like that also for the
> >> auxiliary core.
> > 
> > I suppose my only contribution right now is that for another project
> > where we have U-Boot (on the M4) kicking off NuttX we've had to do a
> > custom command to stack pointer thing, I agree with the need to add some
> > way to easily kick these cases off.
> 
> So the NuttX image was also kind of a raw image? Is that command
> upstream?

The NuttX image is the "normal" raw cortex-m image format (everyone else
just writes it to flash and boots directly).  I haven't pushed the
patches upstream as the rest of the platform also isn't ready to go
upstream.

-- 
Tom
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