Re: [Libunwind-devel] Minimum Linux Version requirements for libunwind?

[Luke Diamand]

On 22 May 2018 at 00:55, John Knight <address@hidden> wrote:
> Hi,
>
>
>
> I am trying to get libunwind to work on an ARM processor running an older
> version of linx (version 3.14.77).  I am wondering if there are any
> particular requirements of the Linux kernel or supporting libraries that
> would prohibit me from running on this older kernel?  If so, what is the
> minimum kernel version required for libunwind?

I don't think it has any special kernel dependencies unless you're
going to a really old kernel version (?). I'm using libunwind with
3.10.

>
> This kernel does NOT have support of backtrace()… my understanding is that
> support came with glibc in version 3.2 which had kernel support for it.  The
> lack of a backtrace has led me to try and use libunwind as an alternative to
> give me a stack backtrace when my program SEG faults.

I didn't think backtrace was a kernel feature - doesn't it live in
glibc? And uses unwind tables generated by gcc/g++ together with the
unwinding code in libstdc++ (as per the ABI).

If you're using glibc's backtrace() with unwind tables rather than
frame pointer unwinding then you'll need a gcc that's new enough to
generate it (and enable generation). That's been mostly there for a
decade or more, but I think a bug was fixed recently (gcc 4.9.4/5.2
timeframe) for some obscure corner-cases.

But back to your question, I think the oldest kernel version I've used
libunwind with is 3.0 with glibc=2.18 and gcc=4.9.

Luke