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etho Device Not Found Redhat Linux Kenel. How to Troubleshoot

Troubleshoot whether etho device is install the module or not
1)check the ethernet driver type
#lspci | grep Ethernet
02:00.0 Ethernet controller: Advanced Micro Devices [AMD] 79c970 [PCnet32 LANCE] (rev 10)
lspci It will list of PCI device.
2)How To Get The Ethernet Device Driver Type
#dmesg | grep eth
r8169: eth0: link up
r8169: eth0: link up
Another Way
2.1)check the configuration file /etc/modprobe.conf file whether the alias entry is there for ethernet device.
alias eth0 pcnet32
/etc/modprobe.conf it contain the list of kernel module.
3)using lsmod command find the device kernel module  is installed or not.
[root@server ~]# lsmod | grep pcnet
pcnet32 35269 0
mii 9409 1 pcnet32
Here it is list out So that I can confirm pcnet32 etho device is installed perfectly, I found eth0 device also in ifconfig output.
#find / -name pcnet*
.ko file represent as Kernel Object on kernel modules (loadable modules ) on Linux

I check in the Other system | Here eth0 kernel Module is Not Installed
1)#lspci | grep Ethernet
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 02). rtl8129 -RTL-8139/8139C/8139C+ (rev 10)- realtek ethernet driver
2)#/etc/modprobe.conf (or) #
dmesg | grep eth
alias etho rtl8129
3)# lsmod | grep rtl8129
But in the lsmod it will not list out the any modules for rtl8129.
For that reason it will not find the eth0 device
while I check the List of ip address using ifconfig, I didn't get any Ethernet device eth0
and then I restart the realtek ethernet driver eth0 network service I got the following error message.
rtl8129 device eth0 does not seem to be present, delaying initialization.rtl8129 -RTL-8139/8139C/8139C+ (rev 10)- realtek ethernet driver

Study How Ethernet Driver Module is configured
1)cat /etc/modprobe.conf
alias eth0 r8169
if it is not list out then we have use modprobe
3)# ethtool -i eth0
version: 7.3.21-k6-1-NAPI
firmware-version: N/A
bus-info: 0000:01:01.0
4)#modinfo <MODULE-NAME> [ Get the detail about module ]
# modinfo r8169
filename:       /lib/modules/2.6.18-238.el5/kernel/drivers/net/r8169.ko
version:        2.3LK-1-NAPI
license:        GPL
description:    RealTek RTL-8169 Gigabit Ethernet driver
author:         Realtek and the Linux r8169 crew <netdev@vger.kernel.org>
srcversion:     16F31D07BEA1F8B3051DFC3
alias:          pci:v00000001d00008168sv*sd00002410bc*sc*i*
depends:        mii
vermagic:       2.6.18-238.el5 SMP mod_unload gcc-4.1
parm:           rx_copybreak:Copy breakpoint for copy-only-tiny-frames (int)
parm:           use_dac:Enable PCI DAC. Unsafe on 32 bit PCI slot. (int)
parm:           debug:Debug verbosity level (0=none, ..., 16=all) (int)
module_sig:     883f3504d2f6ef9c099fb4d84a418b6112a83109d11655e8268c648ab532bbf613bb75b24

/etc/modprobe.conf File
1)also used to set convenient aliases.
2)set the module option.
3)set the Linux kernel module automtically at boot time.

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