14.01.2026 00:16:37 Andre Przywara <[email protected]>: > On Tue, 10 Jun 2025 07:38:54 +0200 > Lukas Schmid <[email protected]> wrote:
Hi Andre, > > Hi Lukas, > >> Boards using MAC addresses stored in EEPROM via the device tree's >> `nvmem-cells` mechanism may already have a valid MAC loaded by the >> device model. However, setup_environment() currently ignores this >> and generates a fallback address from the SoC SID if no environment >> variable is set. >> >> This leads to a mismatch warning during boot when the kernel or U-Boot >> detects the MAC from nvmem and compares it to the environment. >> >> This patch checks whether the corresponding ethernet device node >> has a `nvmem-cells` property and skips generating a fallback MAC >> if it does, thus avoiding redundant or incorrect ethaddr setup. > > So while this seems like a pragmatic solution, I feel it's not the > right one: This "peeking into the DT to skip something" sounds > backwards. You have probably investigated this more thoroughly, but how > does this work here? Did the generic code already parse the MAC address > and put it somewhere, and our code here was about to overwrite it? Or > will the generic code later fill the gap, if the sunxi code didn't set a > MAC address based on the SID? At the time of running setup_environment is not yet set as a environment variable and U-Boot will also not try to set it later since sunxi already set one. I did not find a way in setup_env to check otherwise if there already is a valid Mac somewhere. U-Boot does know however that there is a different mac intended for the interface as it throws a Mac address mismatch warning. > > I feel like the sunxi code is to blame here for doing it at the wrong > time or using its own method instead of coordinating with the generic > code, so I'd rather fix this properly than papering over it here. > > I will help you find a better solution, but if you can dump here what > you learned, I'd be grateful, as I am too lazy atm to chase down the > code ;-) > > Cheers, > Andre > >> This improves compatibility with nvmem-based MAC provisioning and >> aligns U-Boot behavior with Linux. >> >> Signed-off-by: Lukas Schmid <[email protected]> >> --- >> board/sunxi/board.c | 15 ++++++++++++++- >> 1 file changed, 14 insertions(+), 1 deletion(-) >> >> diff --git a/board/sunxi/board.c b/board/sunxi/board.c >> index ac9cefc6..41b85c66 100644 >> --- a/board/sunxi/board.c >> +++ b/board/sunxi/board.c >> @@ -774,10 +774,23 @@ static void setup_environment(const void *fdt) >> return; >> >> for (i = 0; i < 4; i++) { >> + const char *alias; >> + int nodeoffset; >> + int len; >> + const fdt32_t *prop; >> + >> sprintf(ethaddr, "ethernet%d", i); >> - if (!fdt_get_alias(fdt, ethaddr)) >> + alias = fdt_get_alias(fdt, ethaddr); >> + if (!alias) >> continue; >> >> + nodeoffset = fdt_path_offset(fdt, alias); >> + if (nodeoffset >= 0) { >> + prop = fdt_getprop(fdt, nodeoffset, "nvmem-cells", &len); >> + if (prop && len > 0) >> + continue; >> + } >> + >> if (i == 0) >> strcpy(ethaddr, "ethaddr"); >> else
