[lldb-dev] Current quality/support of lldb on 32-bit Linux systems

[Todd Fiala]

Hi Matthew,

I am working on Linux lldb, but currently I am focused on the x86_64 build,
specifically on Ubuntu LTS systems (so 12.04 right now, until we bump up to
the next one).

My only experience with the 32-bit version on Ubuntu 12.04 x86 was that I
could *not* build it using a configure/(g)make Debug+Asserts build as the
compiler/linker would run out of memory.  I did get it to make it past
several OOM situations, but could never get past liblldb.so linkage using
gcc 4.8.2 on a debug build.  When I switched to a release build
(optimizations enabled, no debug info in the lldb build), then I could make
it through the build process.

As to the quality question as it pertains to Linux x86_64 (and probably
Linux as a whole): I have run into several what I'd call significant bugs
where I could not debug development work without first fixing a bug in
lldb.  The good news is that these bugs are getting fixed now as my team
hits them.

On a related note: in an effort to increase confidence in the state of the
code, we are in the process of gathering some code coverage information for
lldb under Linux x86_64 when running the local tests.  This would be a
first approximation as to how much work we may need to do to ensure we've
got lldb Linux running reasonably reliably.  I'll make an attempt to
characterize those results once I have them.  (Right now the
gcov/lcov-built lldb is crashing when run, so I need to track that down
first).  It is likely that x86 Linux will share similar results as the
x86_64 side w/r/t reliability.

I hope that helps, Matthew.

Sincerely,
Todd Fiala


On Wed, Feb 12, 2014 at 1:47 AM, Matthew Gardiner <mg11 at csr.com> wrote:

> Hi
>
> Could somebody please make a statement on the current quality of building
> lldb on 32-bit linux systems, and then using the lldb built to debug 32-bit
> linux processes?
>
> I'm currently using a virtual box guest with access to only 2.3GB of the
> hosts RAM and really struggling. I have managed to build (with gcc-4.8.2)
> lldb without debug symbols, but any attempt to build with debugging just
> results in the kernel (I think) killing the ld invocation.
>
> When I do manage to build an lldb, I'm finding that the debug experience
> is a bit shaky, e.g. the register reading layer seems to be inaccurate, and
> the inferior process status is often misreported.
>
> I am happy to contribute somewhat in this area (I have some wait/ptrace
> etc. experience) - but I wondered whether my continued exploits into
> 32bit-linux were actually worthwhile...
>
> Any advice appreciated,
> Matthew Gardiner
>
>
>
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-- 
Todd Fiala | Software Engineer | tfiala at google.com | 650-943-3180
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