It seems that bytes 13-14 of the SID / bytes 1-2 from word 3 of the SID
are always 0 on H3 making it a poor candidate to use as source for the
serialnr / mac-address, and the other non constant words (1 and 2) also
have quite a few bits which are the same for some boards,
This commits switches to using words 1 - 3 ex-or-ed together to get a
more unique value for the mac-address / serialnr.
Cc: Chen-Yu Tsai <w...@csie.org>
Cc: Corentin LABBE <clabbe.montj...@gmail.com>
Cc: Amit Singh Tomar <amittome...@gmail.com>
Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
Changes in v2:
-ex-or all 3 words together instead of picking a different word
---
board/sunxi/board.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/board/sunxi/board.c b/board/sunxi/board.c
index ef3fe26..e0734fb 100644
--- a/board/sunxi/board.c
+++ b/board/sunxi/board.c
@@ -623,6 +623,21 @@ static void setup_environment(const void *fdt)
ret = sunxi_get_sid(sid);
if (ret == 0 && sid[0] != 0 && sid[3] != 0) {
+#ifdef CONFIG_MACH_SUN8I_H3
+ /*
+ * The single words 1 - 3 of the SID have quite a few bits
+ * which are the same on many models on the H3, so we ex-or
+ * them together to get a bit more unique value.
+ *
+ * Note we only do this on the H3 as we cannot change the
+ * algorithm on other SoCs since those have been using
+ * fixed mac-addresses based on only using word 3 for a
+ * a long time and changing a fixed mac-address with an
+ * u-boot update is not good.
+ */
+ sid[3] ^= sid[1] ^ sid[2];
+#endif
+
/* Ensure the NIC specific bytes of the mac are not all 0 */
if ((sid[3] & 0xffffff) == 0)
sid[3] |= 0x800000;
--
2.7.4
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