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Re: ARM kernel cross compilation issues for iMX53

On Fri, Mar 16, 2012 at 4:51 PM, Mike Thompson <mpthompson@gmail.com> wrote:
> Robert,
> I've had my iMX53 Quick Start for a few days now and I've been spending my
> time getting a basic stable Debian configuration on it.  I hope you don't
> mind me asking a few questions about the configuration you documented at:
> http://eewiki.net/display/linuxonarm/i.MX53+Quick+Start
> At this point, I'm building your kernel and what I believe is
> called the 2.6.35_11.01.00 kernel included with the Freescale BSP and LTIB
> utility for the i.MX53 Quick Start.  I'm trying to understand the
> differences between the two so I can learn by comparing and contrasting.
> One of the first problems I ran into is that I can't build a working u-boot
> using LTIB.  Included with the BSP is a prebuilt u-boot.bin file that does
> work, but there isn't documentation as to where it came from or any
> suggestion why the u-boot.bin I build with LTIB is different than the
> pre-built one supplied with the BSP.  Following your instructions, I can
> easily build a more modern, version of u-boot which works great.  However,
> seems have some known incompatibilities regarding how the UARTs are clocked
> with older kernels.  Until I can figure out how to correct this, I get
> garbage out the serial port when booting other kernels as Linux switches to
> using its tty serial drivers about half-way through the boot.  I notice you
> have a local patch tweaking the UART clock and I'll see if I can work that
> back into the other kernels.

Yeah, i biseced it down to (and reverted)
"ENGR00141363-ARM-imx53-clock-change-di0-clock.patch" from both
freescale's 2.6.35 11.09.01 bsp, which fixes the uart clock

> Anyway, the question I have for you is where does your kernel come from?  It
> seems to come directly from the mailine kernel at kernel.org using the
> following URL:
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> This would seem to imply that it's missing most, if not all, the dozens of
> kernel patches that Freescale applies to the same version of the kernel
> built with LTIB.  Is this a correct assumption on my part?  Or, have the
> Freescale patches made it into the mainline Linux kernel?  Also, how are you
> specifically requesting the branch of the kernel?  Unfortunately,
> I'm still pretty ignorant of how git works and I don't see how this is done.

That's okay, everyone's new to git at some point..

Basicly if you look at freescale's opensource tree:


You'll find, that most of the '2.6.35' tags have a common ancestory to

So basically freescale checked out, then spent 3 years
applying patch after patch after patch.. ;)

So all my script does, it checks out from the "linux-stable"
tree which is combination of torvalds tree and all the stable
branches..  Then i pull freescale's patch set, and since i have the
common ancestory it all merges nice and clean.. Then i also revert one
commit to fix the serial output..

so simple:

git checkout v2.6.35.3 -b new-branch-based-off-
git pull http://opensource.freescale.com/pub/scm/imx/linux-2.6-imx.git
git revert --no-edit <some sha that i can't remember for:

> I can successfully boot your kernel, but message 'usb wakeup is here' is
> output on the serial console every two seconds or so which makes doing
> anything very painful.  I don't know how to turn this off and I presume it's
> related to something you mentioned about usb support not being fully
> supported in the mainline kernel yet for the iMX53.  I guess I need to tweak
> the configuration settings in the kernel to see if I can silence this
> message.

humm, strange which usb port? otg/ehci, i haven't see that one. btw is
this the new "R" board, next to the ddr, there should be a silkscreen
with the model number with a "-R-" or something..

> Finally, I'm wondering if you can comment on the stability of the
> kernel built by your instructions.  Is still very much a work
> in progress, or is it working for you well enough to other aspects of
> porting Debian to the iMX53.  I suspect it's still a work in progress, but
> perhaps I'm just doing some things wrong.

Basically my script to build the "" kernel from freescale
is nothing more then just to build there kernel with all the closed
source binary blobs included.

I'm actually using the master branch of the "imx-devel" script with my
mx51/mx53 boards. But with no usb/graphics other users might not like
that too much, but it is pure mainline kernel with usb might be coming
in the next rc..  But it's perfectly fine for me in my gcc/kernel arm
test farm.


Robert Nelson

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