Re: [PATCH v2] eal: fail initialization if TSC frequency is zero

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Sep 29, 2026 at 06:42:08AM -0700, Stephen Hemminger wrote:
> On Tue, 29 Sep 2026 09:39:36 +0100
> Bruce Richardson <bruce.richardson@intel.com> wrote:
> 
> > On Mon, Sep 28, 2026 at 04:15:58PM -0700, Stephen Hemminger wrote:
> > > Many parts of DPDK will fail with divide by zero and
> > > other errors if the initialization logic ever TSC hz was ever
> > > determined to be zero. This might happen on a broken get_tsc_freq_arch()
> > > or bad emulation in QEMU.
> > > 
> > > If TSC hz is zero, log the error and propagate back to
> > > fail rte_eal_init().
> > > 
> > > This fix doesn't need to go to stable since it is a purely
> > > theoretical problem; we aren't getting divide by zero reports
> > > from users.
> > >   
> > 
> > How was this discovered? Is there a coverity issue id, or was it just AI
> > discovered?
> 
> It was part of review of pcapng timestamp calculation.
> Kind of funny, AI spotted overflow (which I verified) in the code which
> it had previously helped write.  Then it was asking it self,
> "what if TSC was 0". I didn't see how this could happen unless QEMU
> had some broken CPU emulation.
> 
> To me it seemed best to fail fast and die in a safer manner.
>
Agreed. You can add my ack, either for this version or a new version with
the "set" function renamed as I suggest.

Acked-by: Bruce Richardson <bruce.richardson@intel.com>