[PATCH] net/e1000: fix crash when built with GCC 13

[Bruce Richardson]

On Thu, Oct 16, 2025 at 03:48:41PM +0100, Bruce Richardson wrote:
> On Fri, Oct 10, 2025 at 03:31:51PM +0200, Thierry Herbelot wrote:
> > On 10/10/25 14:58, Ciara Loftus wrote:
> > > The e1000 PMD crashes during initialisation in a Ubuntu 24.04 VM when
> > > compiled with gcc-13 with -O3 optimisations. This patch introduces a
> > > compiler barrier after the register read that was causing the issue.
> > > 
> > > Bugzilla ID: 1691
> > > Fixes: af75078fece3 ("first public release")
> > > Cc: stable at dpdk.org
> > > 
> > > Signed-off-by: Ciara Loftus <ciara.loftus at intel.com>
> > 
> > Tested-by: Thierry Herbelot <thierry.herbelot at 6wind.com>
> > 
> > The patch fixes the crash at startup.
> > 
> > 	Thanks
> > 
> > 	Thierry
> > 
> > > ---
> > >   drivers/net/intel/e1000/base/e1000_mac.c | 1 +
> > >   1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/drivers/net/intel/e1000/base/e1000_mac.c b/drivers/net/intel/e1000/base/e1000_mac.c
> > > index 2fa97d12a9..41aae86ffe 100644
> > > --- a/drivers/net/intel/e1000/base/e1000_mac.c
> > > +++ b/drivers/net/intel/e1000/base/e1000_mac.c
> > > @@ -1842,6 +1842,7 @@ s32 e1000_id_led_init_generic(struct e1000_hw *hw)
> > >   		return ret_val;
> > >   	mac->ledctl_default = E1000_READ_REG(hw, E1000_LEDCTL);
> > > +	rte_compiler_barrier();
> > >   	mac->ledctl_mode1 = mac->ledctl_default;
> > >   	mac->ledctl_mode2 = mac->ledctl_default;
> > 
> Since adding a compiler barrier is still a workaround (all-be-it a fairly
> unintrusive one), I'm going to hold off this patch until rc2 or rc3 in the
> hopes we get more details as to the exact root cause and why gcc-13 is
> producing code that crashes.
> 
Given no further progress on this, taking this patch into RC2 so at least
we don't experience the issue.

Applied to next-net-intel.

Thanks,
/Bruce