[Valgrind-users] problem using valgrind on x86 binary

[Mark R. <ma...@cs...>]

I am running Ubuntu 25.10 on wsl on a X86-64 machine. As mentioned
previously, we build a program analysis tool that uses Valgrind to give us
detailed instruction execution information.  I have a test case that runs
correctly both with Valgrind and with our tool (Fjalar) when the test case
is built for X86-64. When the test case is built for X86 it still runs fine
on Valgrind but fails very early when running on FJalar.  I have attached
'--trace-flags' logs of the two cases.  No doubt we have made a mistake
somewhere, but as the failure is an unrecognized instruction while sill
symbolically executing the loader we are unsure how to proceed. Perhaps we
have corrupted this piece of memory - but it's read only, right? If anybody
has any suggestions as to how to proceed with debugging, we would be very
grateful.

-----Original Message-----
From: Paul Floyd via Valgrind-users <val...@li...>
Sent: Friday, January 16, 2026 12:55 PM
To: val...@li...
Subject: Re: [Valgrind-users] set up Valgrind for multiple targets


On 2026-01-16 21:05, Mark Roberts wrote:
> I'd like to be able to use Valgrind on both x86 and x86-64 binaries
> running on my x64-64 linux system.  I quite familiar with building and
> using Valgrind on X86-64 binaries, we use Valgrind as the framework to
> build our DynComp tool to do comparability analysis and type inference
> of C/C++ programs.  I would like to do the same for x86 binaries, but
> I am unsure of the process to setup a secondary target.
>
Hi Mark

What OS are you using?
At the moment I mainly use FreeBSD amd64, Fedora Linux amd64 and a bit of
openSUSE amd64.
For systems where I have the full 32bit subsystem installed then all I have
to do is run configure.
Autoconf should detect both amd64 and x86 and build both of them.
So really all that you need to to is to install the x86 libc. You need the
x86 C++ standard lib if you want to run the regression tests.
openSUSE has removed the x86 startup file from gcc so it can no longer build
x86 binaries (it will still run them). So in some cases you may need to
build a compiler for the platform.

Regards

Paul




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