Difference between revisions of "TFTP server manage netboot kernels"
 
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[[Category:Linux]]
 
[[Category:Linux]]
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=TFTP configuration=
 
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TFTP can manage different configurations, up to 1 per host!
 
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This is how a ThinClient (= netBoot client) will retrieve its configuration:
 
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[[File:TFTP getConfiguration().png|none|TFTP getConfiguration()]]
 
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As you can see you have 3 possibilities:
 
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1. '''MAC @ filter'''. Configuration file name must be:
 
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* Start with ARP type '01-'
 
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* all in lower case hexadecimal
 
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* dash '-' separators instead of ';'
 
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for example a MAC @ 88:99:AA:BB:CC:DD would search for the filename 01-88-99-aa-bb-cc-dd.
 
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2. '''IP @ filter'''. Configuration file name must be:
 
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* host IP / network address in hexadecimal
 
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* all in upper case
 
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e.g. 192.0.2.91 -> C000025B
 
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3. '''Default configuration'''
 
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To learn more about all the available option, check out http://www.syslinux.org/wiki/index.php/PXELINUX.
 
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==Kernel modules and source==
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Your NFS image must have the kernel's libraries and modules, and that must match the kernel's version of the TFTP server!!
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Since Linux kernel is evolving every month or so, you need to backup your kernel's libraries and modules for future use.
  
  
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==Kernel modules and source==
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Create kernel source directory
  
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-- This is an optional step ; but it can avoid many bugs --
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<syntaxhighlight lang="bash">
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# Ubuntu 14.04 - Kernel version 3.13.0.32 (August 2014)
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mkdir -p /tftpboot/sources-images/trusty/lib/modules
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mkdir -p /tftpboot/sources-images/trusty/usr/src
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</syntaxhighlight>
  
  
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If you're using a local kernel as the default NetBoot kernel, then you need to do copy the ''modules'' + ''kernel source'' to every distribution.
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Copy libraries and modules
  
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
# Copy kernel modules
 
# Copy kernel modules
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cp -r /lib/modules/`uname -r` /nfs/trusty/lib/modules
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cp -r /lib/modules/`uname -r` /tftpboot/sources-images/trusty/lib/modules
  
 
# Copy kernel sources
 
# Copy kernel sources
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cp -r /usr/src/linux-headers-`uname -r` /nfs/trusty/usr/src
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cp -r /usr/src/linux-headers-`uname -r` /tftpboot/sources-images/trusty/usr/src/
 
</syntaxhighlight>
 
</syntaxhighlight>
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Note that '''you have to adjust the /nfs'''/XXX
 
  
  
  
  
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=Update TFTP configuration=
  
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==Create NetBoot menu | defaults==
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If you haven't configure TFTP boot yet, check-out [[TFTP_server_PXE_configuration]]
  
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Now, we have to specify which kernel to use and which distributions are available for NetBoot.
 
  
  
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Create the default configuration file:
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To use your new kernel you just need to update TFTP configuration file.
  
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
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Put the following:
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Put the following instead of the previous kernel:
  
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
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# Debian 7.x
 
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LABEL wheezy
 
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    kernel images/wheezy/vmlinuz
 
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    initrd images/wheezy/initrd.img
 
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# Ubuntu 14.04
 
# Ubuntu 14.04
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LABEL trusty
 
 
     kernel images/trusty/vmlinuz
 
     kernel images/trusty/vmlinuz
 
     initrd images/trusty/initrd.img
 
     initrd images/trusty/initrd.img
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</syntaxhighlight>
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=Debug kernel=
  
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# Prompt user for selection
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During NetBoot client startup you might encounter some '''modprobe errors'''.
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PROMPT 1
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# No timeout
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That means the thin client failed to access your kernel's libraries and / or modules.
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TIMEOUT 0
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==NFS image update==
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Access your NFS image by CHROOT /nfs/... + login
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1. Be sure to '''install the kernel's header''' on the NFS image:
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<syntaxhighlight lang="bash">
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apt-get install linux-headers-3.13.0-32
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apt-get install linux-headers-3.13.0-32-generic
 
</syntaxhighlight>
 
</syntaxhighlight>
  
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* Each LABEL is a specific configuration that will displayed on the NetBoot menu.
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<small>''Replace "3.13.0-32" by your version''</small>
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* PROMPT 0 = enable user prompt so you can choose the configuration
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* TIMEOUT 0 = timeout (in seconds) before the default option is chosen. 0 == no timeout
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2. Check the symlinks
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Sometimes when there is just 1 kernel the OS will check for libraries in ''/lib/modules'' instead of ''/lib/modules/kernel-version''
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You can try to copy all the modules files to /lib/modules and adjust the symlink.
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<syntaxhighlight lang="bash">
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cd /lib/modules
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mv 3.13.0-32-generic/* .
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rm -rf 3.13.0-32-generic
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ln -s /lib/modules/ /lib/modules/3.13.0-32-generic
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</syntaxhighlight>
  
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<small>''Replace "3.13.0-27" by your version''</small>
  
  
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Note that I used a reference to "trusty/", that's a folder I need to create later on.
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That should do !

Latest revision as of 10:31, 21 August 2014



Prepare NetBoot kernel

All these steps must be done on the server who has the kernel you want to extract.

Best practice: you should perform the kernel extraction on the TFTP server!


IMPORTANT NOTES

You're about to extract a server kernel and make it available for NetBooting. Make sure that:

  • The kernel has all the drivers installed and configured
  • The kernel doesn't need a reboot
If your client(s) will use some specifics drivers then you MUST install these drivers before going through the following steps.

You need to be very careful, especially if you plan to use some smart-card reader!


Create TFTP Kernel directory

Create the TFTP kernel's folder. You should create 1 folder for each kernel you'd like to provide in NetBoot. 

# Ubuntu 14.04 - Kernel version 3.13.0.32 (August 2014)
mkdir -p /tftpboot/images/trusty


Enable NFS support

Copy initramfs settings for PXE boot 

cp -r /etc/initramfs-tools /etc/initramfs-pxe


Adjust PXE boot configuration 

cd /etc/initramfs-pxe/
vim /etc/initramfs-pxe/initramfs.conf


Add / adjust the following options: 

BOOT=nfs
MODULE=netboot


Copy and prepare kernel

Copy kernel's files 

cp /boot/vmlinuz-`uname -r` /tftpboot/images/trusty/vmlinuz
cp /boot/initrd.img-`uname -r` /tftpboot/images/trusty/initrd.img


Enable NFS boot option 

mkinitramfs -d /etc/initramfs-pxe -o /tftpboot/images/trusty/initrd.img


Adjust rights 

chmod -R 755 /tftpboot/images/


Notes:

  • Do NOT use some symlink for "vmlinuz" and "initrd.img" !! It won't work.
  • If you don't want to use `uname -r` [current kernel version and architecture] then adjust the values to target kernel number + architecture. You can use the `uname -r`command's result.
  • You have to run mkinitramfs for each kernel you'll provide
  • Don't forget to adjust the rights to 755 for every distribution



Kernel modules and source

Your NFS image must have the kernel's libraries and modules, and that must match the kernel's version of the TFTP server!!

Since Linux kernel is evolving every month or so, you need to backup your kernel's libraries and modules for future use.


Create kernel source directory 

# Ubuntu 14.04 - Kernel version 3.13.0.32 (August 2014)
mkdir -p /tftpboot/sources-images/trusty/lib/modules
mkdir -p /tftpboot/sources-images/trusty/usr/src


Copy libraries and modules 

# Copy kernel modules
cp -r /lib/modules/`uname -r` /tftpboot/sources-images/trusty/lib/modules

# Copy kernel sources
cp -r /usr/src/linux-headers-`uname -r` /tftpboot/sources-images/trusty/usr/src/



Update TFTP configuration

If you haven't configure TFTP boot yet, check-out TFTP_server_PXE_configuration


To use your new kernel you just need to update TFTP configuration file. 

vim /tftpboot/pxelinux.cfg/default


Put the following instead of the previous kernel: 

# Ubuntu 14.04
    kernel images/trusty/vmlinuz
    initrd images/trusty/initrd.img


Debug kernel

During NetBoot client startup you might encounter some modprobe errors.

That means the thin client failed to access your kernel's libraries and / or modules.


NFS image update

Access your NFS image by CHROOT /nfs/... + login


1. Be sure to install the kernel's header on the NFS image: 

apt-get install linux-headers-3.13.0-32
apt-get install linux-headers-3.13.0-32-generic

Replace "3.13.0-32" by your version


2. Check the symlinks

Sometimes when there is just 1 kernel the OS will check for libraries in /lib/modules instead of /lib/modules/kernel-version


You can try to copy all the modules files to /lib/modules and adjust the symlink. 

cd /lib/modules
mv 3.13.0-32-generic/* . 
rm -rf 3.13.0-32-generic 
ln -s /lib/modules/ /lib/modules/3.13.0-32-generic

Replace "3.13.0-27" by your version


That should do !

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