[V2] net/intel/e1000: reduce the optimization level for gcc > 11

[Thierry Herbelot]

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 at 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 at 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 at entry=0x62aaf82d8020 <rte_em_pmd>,
>     dev=dev at 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 at entry=146, argv=argv at entry=0x7fffca468898)
>     at ../sources/lib/eal/linux/eal.c:1253

The crash is linked to the use of gcc-13: under 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 at 6wind.com>
---
V2: fix typo in the commit log
    quote long error messages
---
 drivers/net/intel/e1000/base/meson.build | 4 ++++
 drivers/net/intel/e1000/meson.build      | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/net/intel/e1000/base/meson.build b/drivers/net/intel/e1000/base/meson.build
index 4fe86dc6df34..e3631f1adc27 100644
--- a/drivers/net/intel/e1000/base/meson.build
+++ b/drivers/net/intel/e1000/base/meson.build
@@ -22,3 +22,7 @@ base_sources = files(
         'e1000_phy.c',
         'e1000_vf.c',
 )
+# testpmd crashes with gcc > 11 with compiling with default -O3 or -O2
+if (cc.get_id() == 'gcc' and cc.version().version_compare('>=12.0'))
+    base_cflags += '-O1'
+endif
diff --git a/drivers/net/intel/e1000/meson.build b/drivers/net/intel/e1000/meson.build
index 924fe4ecaef5..3a875d1555c2 100644
--- a/drivers/net/intel/e1000/meson.build
+++ b/drivers/net/intel/e1000/meson.build
@@ -23,3 +23,8 @@ if not is_windows
                 'igc_txrx.c',
         )
 endif
+
+# testpmd crashes with gcc > 11 with compiling with default -O3 or -O2
+if (cc.get_id() == 'gcc' and cc.version().version_compare('>=12.0'))
+    cflags += '-O1'
+endif
-- 
2.39.2