From cf1156a60e1d03a752cde0baadbc9ac8118b2a52 Mon Sep 17 00:00:00 2001
From: Christian Poessinger <christian@poessinger.com>
Date: Sun, 21 Feb 2021 18:22:04 +0100
Subject: ethernet: T3163: probe driver for maximum rx/tx ring-buffer size

---
 python/vyos/ethtool.py               | 21 +++++++++++++++++++++
 src/conf_mode/interfaces-ethernet.py | 18 +++++++++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/python/vyos/ethtool.py b/python/vyos/ethtool.py
index e8a339d2f..cef7d476f 100644
--- a/python/vyos/ethtool.py
+++ b/python/vyos/ethtool.py
@@ -33,6 +33,7 @@ class Ethtool:
     #   'tx-esp-segmentation': {'fixed': True, 'on': False},
     # }
     features = { }
+    ring_buffers = { }
 
     def __init__(self, ifname):
         # Now populate features dictionaty
@@ -49,6 +50,16 @@ class Ethtool:
                     "fixed": fixed
                 }
 
+        tmp = cmd(f'ethtool -g {ifname}')
+        # We are only interested in line 2-5 which contains the device maximum
+        # ringbuffers
+        for line in tmp.splitlines()[2:6]:
+            if ':' in line:
+                key, value = [s.strip() for s in line.strip().split(":", 1)]
+                key = key.lower().replace(' ', '_')
+                self.ring_buffers[key] = int(value)
+
+
     def is_fixed_lro(self):
         # in case of a missing configuration, rather return "fixed". In Ethtool
         # terminology "fixed" means the setting can not be changed by the user.
@@ -78,3 +89,13 @@ class Ethtool:
         # in case of a missing configuration, rather return "fixed". In Ethtool
         # terminology "fixed" means the setting can not be changed by the user.
         return self.features.get('udp-fragmentation-offload', True).get('fixed', True)
+
+    def get_rx_buffer(self):
+        # in case of a missing configuration rather return a "small"
+        # buffer of only 512 bytes.
+        return self.ring_buffers.get('rx', '512')
+
+    def get_tx_buffer(self):
+        # in case of a missing configuration rather return a "small"
+        # buffer of only 512 bytes.
+        return self.ring_buffers.get('tx', '512')
diff --git a/src/conf_mode/interfaces-ethernet.py b/src/conf_mode/interfaces-ethernet.py
index bf4650773..e82a3e0f1 100755
--- a/src/conf_mode/interfaces-ethernet.py
+++ b/src/conf_mode/interfaces-ethernet.py
@@ -30,6 +30,7 @@ from vyos.configverify import verify_mtu
 from vyos.configverify import verify_mtu_ipv6
 from vyos.configverify import verify_vlan_config
 from vyos.configverify import verify_vrf
+from vyos.ethtool import Ethtool
 from vyos.ifconfig import EthernetIf
 from vyos.template import render
 from vyos.util import call
@@ -82,11 +83,26 @@ def verify(ethernet):
 
     driver = EthernetIf(ifname).get_driver_name()
     # T3342 - Xen driver requires special treatment
-    if driver == "vif":
+    if driver == 'vif':
         if int(ethernet['mtu']) > 1500 and dict_search('offload.sg', ethernet) == None:
             raise ConfigError('Xen netback drivers requires scatter-gatter offloading '\
                               'for MTU size larger then 1500 bytes')
 
+    ethtool = Ethtool(ifname)
+    if 'ring_buffer' in ethernet:
+        max_rx = ethtool.get_rx_buffer()
+        max_tx = ethtool.get_tx_buffer()
+
+        rx = dict_search('ring_buffer.rx', ethernet)
+        if rx and int(rx) > int(max_rx):
+            raise ConfigError(f'Driver only supports a maximum RX ring-buffer '\
+                              f'size of "{max_rx}" bytes!')
+
+        tx = dict_search('ring_buffer.tx', ethernet)
+        if tx and int(tx) > int(max_tx):
+            raise ConfigError(f'Driver only supports a maximum TX ring-buffer '\
+                              f'size of "{max_tx}" bytes!')
+
     # XDP requires multiple TX queues
     if 'xdp' in ethernet:
         queues = glob(f'/sys/class/net/{ifname}/queues/tx-*')
-- 
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