Re: [PATCH] net/intel/e1000: reduce the optimization level for gcc > 11

[David Marchand <david.marchand@redhat.com>]

On Mon, 6 Oct 2025 at 14:45, Thierry Herbelot
<thierry.herbelot@6wind.com> wrote:
>
> The e1000 PMD stopped working under Ubuntu-24.04 (using gcc-13) when
> compiled with -O3 (default level for all DPDK code). There is a crash
> when starting testpmd:
>
> (gdb) bt
> #0  rte_read32_relaxed (addr=0x1100800e00) at ../sources/lib/eal/include/generic/rte_io.h:290
> #1  rte_read32 (addr=0x1100800e00) at ../sources/lib/eal/include/generic/rte_io.h:345
> #2  e1000_read_addr (addr=0x1100800e00) at ../sources/drivers/net/intel/e1000/base/e1000_osdep.h:106
> #3  e1000_id_led_init_generic (hw=0x1586788c0) at ../sources/drivers/net/intel/e1000/base/e1000_mac.c:1844
> #4  0x000062aaf653c85f in e1000_init_hw_82540 (hw=0x1586788c0)
>     at ../sources/drivers/net/intel/e1000/base/e1000_82540.c:308
> #5  0x000062aaf6db8227 in em_hardware_init (hw=hw@entry=0x1586788c0)
>     at ../sources/drivers/net/intel/e1000/em_ethdev.c:920
> #6  0x000062aaf65340ff in em_hw_init (hw=0x1586788c0) at ../sources/drivers/net/intel/e1000/em_ethdev.c:445
> #7  eth_em_dev_init (eth_dev=eth_dev@entry=0x62aaff346000 <rte_eth_devices>)
>     at ../sources/drivers/net/intel/e1000/em_ethdev.c:314
> #8  0x000062aaf6db8b71 in rte_eth_dev_pci_generic_probe (private_data_size=11240,
>     dev_init=0x62aaf6db8310 <eth_em_dev_init>, pci_dev=0x62ab2853dd90) at ../sources/lib/ethdev/ethdev_pci.h:150
> #9  eth_em_pci_probe (pci_drv=<optimized out>, pci_dev=0x62ab2853dd90)
>     at ../sources/drivers/net/intel/e1000/em_ethdev.c:365
> #10 0x000062aaf646adf5 in rte_pci_probe_one_driver (dr=dr@entry=0x62aaf82d8020 <rte_em_pmd>,
>     dev=dev@entry=0x62ab2853dd90) at ../sources/drivers/bus/pci/pci_common.c:299
> #11 0x000062aaf6a15f7d in pci_probe_all_drivers (dev=0x62ab2853dd90) at ../sources/drivers/bus/pci/pci_common.c:383
> #12 pci_probe () at ../sources/drivers/bus/pci/pci_common.c:410
> #13 0x000062aaf7a485f3 in rte_bus_probe () at ../sources/lib/eal/common/eal_common_bus.c:84
> #14 0x000062aaf670585d in rte_eal_init (argc=argc@entry=146, argv=argv@entry=0x7fffca468898)
>     at ../sources/lib/eal/linux/eal.c:1253
>
> The crash is linked to the use of gcc-13: uner Ubuntu-24.04 testpmd
> compiled with gcc-11 from the same DPDK tree works as expected.
>
> The perfect solution would be for someone to investigate why the
> PMD crashes. However, this depends on Maintainer availability.
>
> A less-perfect solution is to reduce the optimization level
> (like another proposal for net/qede: see Link).
>
> Note: if more regressions are seen in less-frequently used PMDs,
>       maybe we should switch the default optimization level to -O1,
>       (tree-wide) and only rise the optimization level for actively
>       maintained PMDs, which are proven to work as expected with
>       higher optimization levels.
>
> Link: http://patches.dpdk.org/project/dpdk/patch/20250909054023.3263401-1-thierry.herbelot@6wind.com/
> Signed-off-by: Thierry Herbelot <thierry.herbelot@6wind.com>

NAK.
Please RCA this rather than hiding such an issue.


-- 
David Marchand