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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Tony Ambardar <tony.ambardar@gmail.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	Ilya Leoshkevich <iii@linux.ibm.com>, bpf <bpf@vger.kernel.org>,
	dwarves@vger.kernel.org,
	David Marcinkovic <david.marcinkovic@sartura.hr>,
	Luka Perkov <luka.perkov@sartura.hr>,
	Borna Cafuk <borna.cafuk@sartura.hr>,
	Juraj Vijtiuk <juraj.vijtiuk@sartura.hr>
Subject: Re: Problem with endianess of pahole BTF output for vmlinux
Date: Tue, 29 Sep 2020 10:57:17 -0700
Message-ID: <CAEf4BzZHF+KOxSCVeDoKnoLS_U9Qc6rT+tOMy0vA_C8FaFO5yQ@mail.gmail.com> (raw)
In-Reply-To: <CAPGftE_aD6raGXnjhAM6CCMjB2_9C77Z=Xg-=wMwaduTHCp3Pw@mail.gmail.com>

On Mon, Sep 28, 2020 at 11:48 PM Tony Ambardar <tony.ambardar@gmail.com> wrote:
>
> On Mon, 28 Sep 2020 at 21:15, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
> >
> > On Mon, Sep 28, 2020 at 8:41 PM Tony Ambardar <tony.ambardar@gmail.com> wrote:
> > >
> [...]
> > > I can provide 32-bit and 64-bit big-endian system images for running
> > > on QEMU's malta target. These are built using OpenWRT's build system
> > > and include a recent stable bpftool (v5.8.x) and v5.4.x kernel. Is
> > > that sufficient? It would work if manually creating raw or elf-based
> > > BTF files on a build host, then copying into the QEMU target to test
> > > parsing with bpftool (linked with the standard libbpf).
> >
> > That would be great! I intend to run them under qemu-system-arm and
> > supply latest kernel through -kernel option, so kernel itself is not
> > that critical. Same for bpftool, pahole, etc, I'll just supply them
> > from my host environment. So please let me know how I can get ahold of
> > those. Sample qemu invocation command line would be highly appreciated
> > as well. Thank you!
> >
> Sounds good. However, malta is actually a MIPS platform. I've been using it

I don't care about ARM vs MIPS specifically. Needed 32-bit and
big-endian, just to test different variations. MIPS works just fine, I
think.

> a long time because it makes things particularly easy to switch configuration
> between different word-sizes and endianness.
>
> I had some malta mips images ready to go, but if you need ARM I'll need
> to look into building images for big-endian ARM. Big-endian isn't so common
> in the wild, and I'll need to see if OpenWRT supports these, and how to
> configure with QEMU's 'armvirt' target if possible...
>
> > >
> > > For changes to the Linux build system itself (e.g. pahole endian
> > > options and target endian awareness), you would need to set up a
> >
> > I think that shouldn't be a problem and should be handled
> > transparently, even in a cross-compilation case, but let's see.
> >
> > > standard OpenWRT build environment. I can help with that, or simply
> > > integrate your patches myself for testing. As you say, nothing to be
> > > super pumped about...
> > >
> > > Let me know what's easiest and how best to get images to you.
> >
> > Any way you like and can. Dropbox, Google drive, what have you.
> >
> Meantime, I can package up what I have and send you the details. That
> would include images for mips32/64 big-endian and arm32/64 little-endian,
> plus usage examples. Is that still helpful for you?

Yeah, tremendously! After fighting my local qemu setup I managed to
run malta-be image successfully. Thanks a lot, that saves me lots of
gray hair. I'll get to testing this hopefully today-tomorrow, will let
you know if I had any more problems.

>
> Thanks,
> Tony

      parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAPGftE8ipAacAnm9xMHFabXCL-XrCXGmOsX-Nsjvz9wnh3Zx-w@mail.gmail.com>
     [not found] ` <9e99c5301fbbb4f5f601b69816ee1dc9ab0df948.camel@linux.ibm.com>
     [not found]   ` <CAEf4Bza9tZ-Jj0dj9Ne0fmxa95t=9XxxJR+Ce=6hDmw_d8uVFA@mail.gmail.com>
     [not found]     ` <8cf42e2752e442bb54e988261d8bf3cd22ad00f2.camel@linux.ibm.com>
     [not found]       ` <20200909142750.GC3788224@kernel.org>
2020-09-19  7:58         ` Tony Ambardar
2020-09-21 18:19           ` Andrii Nakryiko
2020-09-28 20:18             ` Andrii Nakryiko
2020-09-28 20:27               ` Luka Perkov
2020-09-29  3:41               ` Tony Ambardar
2020-09-29  4:15                 ` Andrii Nakryiko
2020-09-29  6:48                   ` Tony Ambardar
2020-09-29 17:36                     ` Juraj Vijtiuk
2020-09-29 17:57                     ` Andrii Nakryiko [this message]

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