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--- projects:homelab:sfp_gpon_onu:eeprom_editing [2025/03/29 07:31] – [Steps] i2cset param note Andrew Yong
+++ projects:homelab:sfp_gpon_onu:eeprom_editing [2026/03/21 17:21] (current) – clarification on 1000BASE-X linux limitation Andrew Yong
@@ Line 10: / Line 10: @@
     * SFP port(s) (any speed) with I2C bus
     * Packages ''ethtool-full'' ''i2c-tools''
-  * [[https://sfptotal.io/software|SFPTotal Wizard]] (Windows software, only used to calculate checksum at 0x3f)
 ==== Steps ====
-  - On OpenWrt
+  - SSH into OpenWrt
-    - Dump EEPROM:\\ ''ethtool -m //**[ethX]**// raw on > /tmp/sfp.bin''
+  - Run one of the following commands to determine which I2C bus your SFP is on
-  - On Windows desktop
+    * If your router has **a single SFP**:
-    - Copy EEPROM to Windows desktop (run in Windows Terminal):\\ ''scp -O root@192.168.1.1:/tmp/sfp.bin .''
+      - ''%%BUS=$(for bus in /sys/bus/i2c/devices/i2c-*; do b=${bus##*-}; i2cdetect -y -r $b 2>/dev/null | grep -q " 50 " && i2cdetect -y -r $b 2>/dev/null | grep -q " 51 " && echo $b; done)%%''
-    - Open sfp.bin in SFPTotal Wizard
+      - ''echo $BUS'' and check there is a value before proceeding (you can also run the multiple SFP script below to verify the SFP vendor and S/N)
-    - Set the bits in SFPTotal Wizard according to the EEPROM Bits table below
+    * If your router has **multiple SFPs**:
-    - Take note of the checksum in 0x3F (first green byte)
+      - <code>for bus in /sys/bus/i2c/devices/i2c-*; do
-  - On OpenWrt
+    b=${bus##*-}
-    - Set the SFP EEPROM bits in OpenWrt according to the EEPROM Bits table below (you will need to adjust ''-y 5'' to match the i2c bus on your system)
+    if i2cdetect -y -r $b 2>/dev/null | grep -q " 50 " && i2cdetect -y -r $b 2>/dev/null | grep -q " 51 "; then
-      * ''i2cset -y 5 0x50 0x06 0x00''
+        vendor=""
-      * ''i2cset -y 5 0x50 0x0a 0x05''
+        for reg in $(seq 20 35); do
-      * ''i2cset -y 5 0x50 0x0c 0x1f''
+            vendor="$vendor$(printf "\\x$(i2cget -y $b 0x50 $reg | sed 's/0x//')")"
-      * ''i2cset -y 5 0x50 0x3f 0x//**[Refer to SFPTotal Wizard]**//''
+        done
-    - Physically re-seat the SFP
+        serial=""
-    - Verify the new speeds are detected:\\ ''ethtool -m //**[ethX]**//''\\ <code>
+        for reg in $(seq 68 83); do
+            serial="$serial$(printf "\\x$(i2cget -y $b 0x50 $reg | sed 's/0x//')")"
+        done
+        echo ""
+        echo "Bus: $b"
+        echo "├─▶ Vendor: $vendor"
+        echo "└─▶ S/N: $serial"
+    fi
+done</code>
+      - Determine the correct bus number, e.g. 5
+      - ''BUS=5'' (replace 5 with the respective bus number)
+  - Run the following commands to set the SFP EEPROM bits in OpenWrt according to the EEPROM Bits table below
+    - ''i2cset -y $BUS 0x50 0x06 0x00''
+    - ''i2cset -y $BUS 0x50 0x0a 0x05''
+    - ''i2cset -y $BUS 0x50 0x0c 0x1f''
+    - ''%%i2cset -y $BUS 0x50 0x3f $(i2cdump -y -r 0-62 $BUS 0x50 b | awk 'NR>1 {for(i=2;i<=NF;i++) if($i~/^[0-9a-f]{2}$/) {cmd="printf \"%d\" 0x"$i; cmd|getline d; close(cmd); sum+=d}} END {printf "0x%02x", sum % 256}')%%''
+  - Physically re-seat the SFP
+  - Verify the new speeds are detected:\\ ''ethtool -m //**[ethX]**//''\\ <code>
         Supported link modes:   2500baseX/Full
 baseX/Full
@@ Line 35: / Line 51: @@
 ==== EEPROM Bits ====
-^ Address ^ Old Setting ^ New Setting ^
+^  Address  ^  Field  ^  Old Value  ^  New Value  ^  Reason  ^
-| ''0x06'' | ''0x02'' | ''0x00'' |
+|  ''0x06''  |  Ethernet Compliance  |  ''0x02''  |  ''0x00''  |  Clear 1000BASE-LX to avoid advertising conflicting speeds alongside 2500BASE-X  |
-| ''0x0A'' | ''0x00'' | ''0x05'' |
+|  ''0x0A''  |  Extended Compliance  |  ''0x00''  |  ''0x05''  |  Declare 2500BASE-X support  |
-| ''0x0C'' | ''0x0D'' | ''0x1F'' |
+|  ''0x0C''  |  Nominal Bit Rate  |  ''0x0D''  |  ''0x1F''  |  Set to 3100MBd (correct value for 2500BASE-X)  |
-| ''0x3F'' (Checksum) | :!: Use SFPTotal to calculate! :!: ||
+|  ''0x3F''  |  CC_BASE Checksum  |  (varies)  |  (recalculated by ''awk'')  |  Sum of bytes 0x00–0x3E mod 256  |
+|  ''0x5F''  |  CC_EXT Checksum  |  (varies)  |  (unchanged)  |  Not affected by these changes  |
+==== EEPROM Bits (XG-PON/XGS-PON) ====
+> ⚠️ **Warning:** These settings are untested. Proceed with caution.
+Notes:
+  * Due to Linux kernel limitations, only a single speed can be advertised via EEPROM for XG-PON/XGS-PON. Multi-rate combinations (e.g. 2.5/5Gbps, 5/10Gbps, 2.5/5/10Gbps) are not achievable through EEPROM editing alone((Linux's SFP bus driver derives supported speeds solely from EEPROM compliance codes, which only allows a single speed to be declared via the compliance code bytes. Multi-rate support requires either a kernel quirk (hardcoded per vendor/part number in ''sfp.c''), a PHY-emulating module that negotiates speeds independently, or a NIC driver that bypasses the generic SFP bus logic entirely.))
+  * You do not have to update the 0x5F checksum (CC_EXT) unless you edit addresses ''0x40''–''0x5E'', which are out of scope of this guide; but in case you need it, this command will update CC_EXT:\\ ''%%i2cset -y $BUS 0x50 0x5f $(i2cdump -y -r 64-94 $BUS 0x50 b | awk 'NR>1 {for(i=2;i<=NF;i++) if($i~/^[0-9a-f]{2}$/) {cmd="printf \"%d\" 0x"$i; cmd|getline d; close(cmd); sum+=d}} END {printf "0x%02x", sum % 256}')%%''
+=== Fiber Rates (No PHY) ===
+^  Address  ^  Field  ^  Choose only ONE column of values  ^^^^^^
+^  :::  ^  :::  ^  1000BASE-X  ^  2500BASE-X  ^  10GBASE-LR  ^  10GBASE-SR  ^  10GBASE-LRM  ^  10GBASE-ER  ^
+|  ''0x03''  |  10G Ethernet Compliance  |  ''0x00''  |  ''0x00''  |  ''0x20''  |  ''0x10''  |  ''0x40''  |  ''0x80''  |
+|  ''0x06''  |  Ethernet Compliance  |  ''0x02''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |
+|  ''0x0A''  |  Extended Compliance  |  ''0x00''  |  ''0x05''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |
+|  ''0x0C''  |  Nominal Bit Rate  |  ''0x0D'' (1300MBd)  |  ''0x1F'' (3100MBd)  |  ''0x67'' (10300MBd)  |  ''0x67'' (10300MBd)  |  ''0x67'' (10300MBd)  |  ''0x67'' (10300MBd)  |
+|  ''0x3F''  |  CC_BASE Checksum  |  (recalculated by ''awk'')  ||||||
+Notes:
+  * Set ''0x06'' to ''0x00'' (clear 1000BASE-LX) for all configurations above except 1000BASE-X, to avoid advertising conflicting speeds alongside the selected rate
+=== Copper Rates (PHY Emulation Required) ===
+^  Address  ^  Field  ^  Choose only ONE column of values  ^^^^
+^  :::  ^  :::  ^  2500BASE-T  ^  5GBASE-T  ^  10GBASE-T (SFI)  ^  10GBASE-T (SR, 30m)  ^
+|  ''0x03''  |  10G Ethernet Compliance  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |
+|  ''0x06''  |  Ethernet Compliance  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |
+|  ''0x0A''  |  Extended Compliance  |  ''0x1E''  |  ''0x1D''  |  ''0x16''  |  ''0x1C''  |
+|  ''0x0C''  |  Nominal Bit Rate  |  ''0x1F'' (3100MBd)  |  ''0x32'' (5000MBd)  |  ''0x67'' (10300MBd)  |  ''0x67'' (10300MBd)  |
+|  ''0x3F''  |  CC_BASE Checksum  |  (recalculated by ''awk'')  ||||

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