[poky] RT-patch for Yocto-kernel

[Bruce Ashfield]

On Mon, Nov 4, 2013 at 2:31 AM, Keskinarkaus, Teemu
<Teemu.Keskinarkaus at maximatecc.com> wrote:
> Hi,
>
>
>
> In our system we want to use Full RT – kernel configuration. I learned that
> Yocto/Poky Preempt – rt is actually just low latency configuration and not
> the real Full RT as the name falsely suggests. Anyway, that’s not the
> problem after I found it.
>

Hmm. No. The standard/preempt-rt/* branches in the Yocto kernel are the
full -rt patch.

>
>
> There is a patch in the kernel.org that adds the Full RT support for the
> kernel. Unfortunately it doesn’t work right away in Yocto kernel. We use
> emenlow variant of the kernel.
>
>
>
> So I compiled the system and then fixed the patch by applying it to kernel
> sources in build-directory. Then added the  patch to kernel .bbappend file
> so that it would be applied during compilation time.  Or so I thought.
>
>
>
> Now when I try to compile the system do_patch – state for linux-yocto-rt –
> fails.
>
>
>
> Log data follows:
>
> | DEBUG: Executing shell function do_patch
>
> | Deleted branch meta-temp (was 37fdb0c).
>
> | [INFO] validating against known patches  (emenlow-preempt-rt-meta)
>
> Context reduced to (2/2) to apply fragment at 385    ] (\)(88 %))
>
> error: patch failed: drivers/net/ethernet/ti/cpsw.c:374(/)(92 %)%)
>
> | error: drivers/net/ethernet/ti/cpsw.c: patch does not apply
>
> | Context reduced to (1/1) to apply fragment at 1050
>
> | error: patch failed: include/linux/preempt.h:107
>
> | error: include/linux/preempt.h: patch does not apply
>
> | error: patch failed: kernel/sched/core.c:1477
>
> | error: kernel/sched/core.c: patch does not apply
>
> | ERROR. could not update git tree
>
> | ERROR. Could not apply patches for emenlow.
>
> |        Patch failures can be resolved in the devshell (bitbake -c devshell
> linux-yocto-rt)
>
>
>
> If I’m understanding that right it actually applied my patch before the
> emenlow-patch and that’s why it fails.
>
>
>
> What’s the proper way to make kernel patch that big or is there already Full
> RT – patch for emenlow kernel for yocto? We have smaller patches that don’t
> collide with emmenlow patches and they work just fine.

You simply need to make the emenlow BSP compatible with linux-yocto-rt
and use KBRANCH="standard/preempt-rt/base"

And you have the full -rt patch available.

Cheers,

Bruce

>
>
>
> Teemu Keskinarkaus
>
>
>
>
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