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

[Stephen Hemminger]

On Tue, 29 Sep 2026 14:57:54 +0100
Bruce Richardson <bruce.richardson at intel.com> wrote:

> 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 at 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 at intel.com>
>  

I also updated comment to rte_get_tsc_hz() since existing
comment implies the value could be different on each lcore.