[Buildroot] [Bug 10161] New: unable to build u-boot.imx reliably

[Buildroot] [Bug 10161] New: unable to build u-boot.imx reliably

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10161

            Bug ID: 10161
           Summary: unable to build u-boot.imx reliably
           Product: buildroot
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P5
         Component: Other
          Assignee: unassigned at buildroot.uclibc.org
          Reporter: yurovsky at gmail.com
                CC: buildroot at uclibc.org
  Target Milestone: ---

Created attachment 7156
  --> https://bugs.busybox.net/attachment.cgi?id=7156&action=edit
hacky workaround

I'm unable to build the u-boot.imx image (for Freescale i.MX SoCs) reliably
(that is, it generally works but if I "slow down" my system by making the CPUs
busy, or use a slower machine, I can break the build very often).

The issue seems to be in u-boot's build system but I'm not certain so I wanted
to check if there's anything that we might be doing in buildroot that should be
done differently before taking this up with them.

To build the i.MX image the config should have:

BR2_TARGET_UBOOT_FORMAT_IMX=y

(and be one of the i.MX targets anyway since we need a board target in u-boot).
What happens is u-boot will process a template config file and eventually
mkimage is run to generate the .imx image using the .cfg files in the board
directory. The build will fail because the processed .cfg isn't found and it
seems that the .cfg was in fact built, it just raced with the image step.

I have a workaround that, while hacky, shows that we can prevent the problem by
making those steps less parallel (attached).

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[Buildroot] [Bug 10161] unable to build u-boot.imx reliably

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10161

--- Comment #1 from Arnout Vandecappelle <arnout@mind.be> ---
Without any other evidence, we can only assume it's an issue with the U-Boot
build system. And something that is very hard to fix at the Buildroot level:
since we don't know which U-Boot version is being used, we can't easily patch
it.

I have done a quick review of the Makefile for imx in the U-Boot source, and it
looks good to me. But you haven't really given sufficient information to
pinpoint the problem. You should try to reproduce with V=1 so we get usable
output. And also try to reproduce outside of Buildroot - should be easy, you
basically just have to run 'make CROSS_COMPILE=... ARCH=arm ..._defconfig; make
CROSS_COMPILE=... ARCH=arm V=1 u-boot.imx'.

Or perhaps it only happens when you try to build u-boot.imx and u-boot-dtb.imx
in parallel?

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[Buildroot] [Bug 10161] unable to build u-boot.imx reliably

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10161

--- Comment #2 from Andrey Yurovsky <yurovsky@gmail.com> ---
Sorry, I meant to say I tried 2017.05 and 2017.07. I'll reproduce this and post
output, however the output is a bit unclear (even at V=1) because this is a
parallel make problem so we're dealing with some kind of race condition.

I believe that I can only reproduce it by building the way buildroot does (one
make invocation with multiple targets), the attached workaround patch shows
that we avoid the problem by invoking make twice.

I'll try to reproduce this with u-boot on its own. The Makefile portions
dealing with building a .imx image have changed significantly between 2017.05
and 2017.07.

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[Buildroot] [Bug 10161] unable to build u-boot.imx reliably

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10161

--- Comment #3 from Thomas Petazzoni <thomas.petazzoni@free-electrons.com> ---
I also believe that Buildroot is not at fault here, it's U-Boot build system
that doesn't have the proper dependencies. Could you report this issue to
upstream U-Boot instead ? I'm pretty sure you can reproduce it outside of
Buildroot by running the same build commands.

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[Buildroot] [Bug 10161] unable to build u-boot.imx reliably

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10161

Thomas Petazzoni <thomas.petazzoni@free-electrons.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WONTFIX
             Status|NEW                         |RESOLVED

--- Comment #4 from Thomas Petazzoni <thomas.petazzoni@free-electrons.com> ---
This problem clearly seems to be a U-Boot issue, so it should be reported to
the upstream U-Boot project instead.

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