On Wed, Jul 08, 2026 at 04:44:24PM +0300, Dima Ruinskiy wrote: > Some systems implement a system MAC address object in the ACPI table, > using either \\_SB.AMAC or \\MACA object names. This system MAC address, > when enabled, is intended to override the permanent MAC address of the > network controller. > > Implement lookup of the relevant ACPI object names and use them to > initialize the MAC address. > > On systems where the feature is disabled or unsupported, the ACPI objects > do not exist or do not contain a valid Ethernet MAC, causing a fallback > to the existing MAC address initialization path. This patch works as expected and solves the connection issue when the MAC passthrough feature is enabled.
Tested-by: Chia-Lin Kao (AceLan) <[email protected]> > > Assisted-by: GitHub-Copilot:claude-opus-4.7 > Signed-off-by: Dima Ruinskiy <[email protected]> > --- > drivers/net/ethernet/intel/igc/igc_main.c | 64 ++++++++++++++++++++++- > 1 file changed, 62 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/intel/igc/igc_main.c > b/drivers/net/ethernet/intel/igc/igc_main.c > index 82800a4a6d6c..83eb8953e954 100644 > --- a/drivers/net/ethernet/intel/igc/igc_main.c > +++ b/drivers/net/ethernet/intel/igc/igc_main.c > @@ -11,6 +11,8 @@ > #include <net/pkt_sched.h> > #include <linux/bpf_trace.h> > #include <net/xdp_sock_drv.h> > +#include <linux/acpi.h> > +#include <linux/hex.h> > #include <linux/pci.h> > #include <linux/mdio.h> > > @@ -7116,6 +7118,57 @@ static enum hrtimer_restart > igc_qbv_scheduling_timer(struct hrtimer *timer) > return HRTIMER_NORESTART; > } > > +static bool igc_get_acpi_mac_passthru(u8 *mac) > +{ > + static const struct { > + const char *name; > + acpi_object_type type; > + u32 length; > + } sources[] = { > + { "\\_SB.AMAC", ACPI_TYPE_BUFFER, 23 }, > + { "\\MACA", ACPI_TYPE_STRING, 22 }, > + }; > + struct acpi_buffer buffer; > + union acpi_object *obj; > + bool mac_found = false; > + acpi_status status; > + u8 buf[ETH_ALEN]; > + int i; > + > + if (!IS_ENABLED(CONFIG_ACPI)) > + return false; > + > + for (i = 0; i < ARRAY_SIZE(sources) && !mac_found; i++) { > + buffer.length = ACPI_ALLOCATE_BUFFER; > + buffer.pointer = NULL; > + > + status = acpi_evaluate_object(NULL, (char *)sources[i].name, > + NULL, &buffer); > + if (ACPI_FAILURE(status)) > + continue; > + > + obj = buffer.pointer; > + if (!obj || obj->type != sources[i].type || > + obj->string.length != sources[i].length) > + goto free_obj; > + > + if (strncmp(obj->string.pointer, "_AUXMAC_#", 9) || > + obj->string.pointer[21] != '#') > + goto free_obj; > + > + if (hex2bin(buf, obj->string.pointer + 9, ETH_ALEN) || > + !is_valid_ether_addr(buf)) > + goto free_obj; > + > + ether_addr_copy(mac, buf); > + mac_found = true; > +free_obj: > + kfree(obj); > + } > + > + return mac_found; > +} > + > /** > * igc_probe - Device Initialization Routine > * @pdev: PCI device information struct > @@ -7279,9 +7332,16 @@ static int igc_probe(struct pci_dev *pdev, > } > > if (eth_platform_get_mac_address(&pdev->dev, hw->mac.addr)) { > - /* copy the MAC address out of the NVM */ > - if (hw->mac.ops.read_mac_addr(hw)) > + /* Look for a system-provided MAC in the ACPI table before > + * falling back to reading the address from the NVM. > + */ > + if (igc_get_acpi_mac_passthru(hw->mac.addr)) { > + netdev->addr_assign_type = NET_ADDR_STOLEN; > + dev_info(&pdev->dev, "Using ACPI pass-thru MAC addr > %pM\n", > + hw->mac.addr); > + } else if (hw->mac.ops.read_mac_addr(hw)) { > dev_err(&pdev->dev, "NVM Read Error\n"); > + } > } > > eth_hw_addr_set(netdev, hw->mac.addr); > -- > 2.44.0 >
