Weird signal issues using yocto's warrior busybox (aarch64) when memory is cached

[Sergio Paracuellos]

Hi all,

On Fri, Jan 31, 2020 at 9:47 AM Sergio Paracuellos
<sergio.paracuellos at gmail.com> wrote:
>
> Hi Stefan,
>
> On Fri, Jan 31, 2020 at 8:41 AM Stefan Seyfried
> <stefan.seyfried at googlemail.com> wrote:
[snip]
>
> After looking to different core files it seems I am able to reproduce
> issues and seems to be related with a fork() -> execl pattern when
> running different programs. That seems the way the shell exec
> processes. I think I should also try to reproduce this behaviour with
> a more accurate C program doing the same :-). I don't want to make
> busybox the real guilty here, but until now all my problems are
> related with it, and that's why I am asking here :)). I'll try it and
> report here afterwards.

I was able to reproduce this bug also with C programs using the
mentioned pattern and after a deep research of what was happening
there I found the problem. It was a problem related with the
remoteproc nodes in the device tree. I use remoteproc to start , stop
and load the firmware in the ARM R5 cores from the linux side. These
cores use for the stack, interrupts, etc its own Tightly-Coupled
Memory but to share the acquired data with the linux side a shared
memory is used through libmetal. The shared memory is located in the
DDR and in the linux side is handled through uio kernel apis managed
in user space with libmetal also. In order this to work properly all
the shared memory range shall be defined as reserved memory also for
the remoteproc as 'no-map' and after that just define the uio's kernel
nodes with the memory ranges. The 'no-map' part was the problem here.
So it is properly working now. There was not an error with busybox at
all, so I apologize and really really sorry for the noise.

> >
> > BTDT.
> >
>
> Thanks for your help. Very appreciated.

Thanks to all again for your effort and advices.

Best regards,
    Sergio Paracuellos
>
> Best regards,
>      Sergio Paracuellos
>
> > >> I just had a USB thumb drive corrupt a file with no warning, so it was
> > >> fresh on my mind.
> >
> > --
> > Stefan Seyfried
> >
> > "For a successful technology, reality must take precedence over
> >  public relations, for nature cannot be fooled." -- Richard Feynman
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