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pxe无盘启动
PXE is a great solution for booting a diskless computer (or a computer without an OS installed). This method is often used for terminal stations and OS mass installation.
PXE是引导无盘计算机(或未安装操作系统的计算机)的绝佳解决方案。 此方法通常用于终端站和OS批量安装。
Stock ubuntu (16.04) in pxe-mode can mount rootfs only from NFS. But this is not a great idea: any difficulties with the network/NFS server and the user gets problems.
pxe模式下的常规ubuntu(16.04)只能从NFS挂载rootfs。 但这不是一个好主意：网络/ NFS服务器的任何困难和用户都会遇到问题。
In my opinion, it's best to use other protocols, such as http/ftp. Once booting, you will have an independent system
我认为，最好使用其他协议，例如http / ftp。 一旦启动，您将拥有一个独立的系统
You should add information about the limits of applicability of the proposed solution and what are the dependencies and restrictions.
您应该添加有关建议的解决方案的适用性限制以及相关性和限制的信息。
PXE (Preboot Execution Environment) is a special method for booting a computer from the bios / EFI. How it works (simplified scheme):
PXE(预引导执行环境)是一种从BIOS / EFI引导计算机的特殊方法。 工作原理(简化方案)：
Keep in mind that TFTP is a slow protocol. It works around UDP with a small block size (512K). Of course, you can increase this value, but this is a way of unstable operation.
请记住，TFTP是一个缓慢的协议。 它适用于具有小块大小(512K)的UDP。 当然，您可以增加此值，但这是不稳定操作的一种方式。
A better solution:
更好的解决方案：
Steps to solve the task:
解决任务的步骤：
I used squashfs for rootfs (the simplest way is to create squashfs from installed ubuntu). Overlayfs is necessary to make rootfs writable.
我将squashfs用于rootfs(最简单的方法是从已安装的ubuntu创建squashfs)。 覆盖是使rootfs可写的必要条件。
Supported protocols are http/ftp, but you can try to add others via curl/other software.
支持的协议是http / ftp，但是您可以尝试通过curl /其他软件添加其他协议。
There are 2 places where you can customize initramfs in ubuntu:
您可以在2个地方自定义ubuntu中的initramfs：
I'll use /usr/share/initramfs-tools. First, I added needed support modules in initramfs:
我将使用/ usr / share / initramfs-tools。 首先，我在initramfs中添加了所需的支持模块：
boozlachu@comp:~$ cat /usr/share/initramfs-tools/modules.d/pxeoverlayfssquashfs
Next, I wrote a boot script that does all the work:
接下来，我编写了一个启动脚本来完成所有工作：
boozlachu@comp:~$ cat /usr/share/initramfs-tools/scripts/pxe #!/bin/bashmountroot(){ maxTryCount=5 squashfsFile="/tmp/rootfs.squashfs" squashfsMountPoint="/mnt/ro" tmpfsMountPoint="/mnt/rw" overlayfsUppderDir="$tmpfsMountPoint/upper" overlayfsWorkDir="$tmpfsMountPoint/work" overlayfsDir="/mnt/overlayfs" tryCount="1" # run udevadm wait_for_udev 10 # parce kernel cmdline args. rooturl needed for x in $(cat /proc/cmdline); do case $x in rooturl=*) export rooturl=${x#rooturl=} ;; maxTryCount=*) export maxTryCount=${x#maxTryCount=} ;; esac done log_begin_msg "Loading modules" modprobe squashfs || panic "can't modprobe squashfs" modprobe af_packet || panic "can't modprobe af_packet" modprobe overlay || panic "can't modprobe overlayfs" log_success_msg "modules loaded" log_begin_msg "Configure network" configure_networking || panic "Can't configure network" log_success_msg "Network configured" log_begin_msg "Download rootfs" while [ ! -f ${squashfsFile} ] && [ ${tryCount} -le ${maxTryCount} ]; do wget ${rooturl} -O ${squashfsFile} || log_failure_msg "Can't download rootfs, count ${tryCount}" tryCount=$(( ${tryCount} + 1 )) sleep 0.5 done if [ -f ${squashfsFile} ] then log_success_msg "Rootfs downloaded" else panic "Can't download rootfs" fi log_begin_msg "Mount rootfs" mkdir -p $squashfsMountPoint mount -t squashfs -o loop $squashfsFile $squashfsMountPoint || panic "Can't mount rootfs" log_success_msg "Rootfs mounted" log_begin_msg "Mount tmpfs" mkdir -p $tmpfsMountPoint mount -t tmpfs none $tmpfsMountPoint || panic "Tmpfs mount failed " log_success_msg "Tmpfs mounted" log_begin_msg "Mount overlayfs" mkdir -p $overlayfsUppderDir $overlayfsWorkDir $overlayfsDir mount -t overlay overlay -o lowerdir=$squashfsMountPoint,upperdir=$overlayfsUppderDir,workdir=$overlayfsWorkDir $overlayfsDir \ || panic "Overlayfs mount failed" log_success_msg "Overlayfs mounted" log_begin_msg "Move tmpfs and squashfs to new root" mkdir -p $overlayfsDir/$tmpfsMountPoint $overlayfsDir/$squashfsMountPoint mount --move $squashfsMountPoint $overlayfsDir/$squashfsMountPoint || panic "squashfs move failed" mount --move $tmpfsMountPoint $overlayfsDir/$tmpfsMountPoint || panic "tmpfs move failed" log_success_msg "Tmpfs and squashfs moved" log_begin_msg "Move overlayfs to new root" mount --move $overlayfsDir ${rootmnt} || panic ""} The script has a lot of messages for understanding how it works.
该脚本有很多消息，可帮助您理解其工作原理。
After the modules and script, add your need to generate new initramfs:
在模块和脚本之后，添加生成新initramfs的需求：
boozlachu@comp:~$ sudo update-initramfs -c -k all
The simplest method:
最简单的方法：
I don't recommend this way for production since you'll have a very large squashfs (not the best idea for pxe)!
我不建议您以这种方式进行生产，因为您会有非常大的南瓜(对于pxe来说不是最好的主意)！
I use pxelinux as a pxe bootloader. It's an easy way. My pxe servers are Debian 10, tftp-hpa,dhcpd, and lighttpd. I’ll omit the installation details, but I’ll show the important info.
我使用pxelinux作为pxe引导程序。 这是一个简单的方法。 我的pxe服务器是Debian 10，tftp-hpa，dhcpd和lighttpd。 我将省略安装细节，但会显示重要信息。
TFRP server file struct (/srv/tftp is root dir fot tftp-hpa):
TFRP服务器文件结构(/ srv / tftp是fdir tftp-hpa的根目录)：
root@debian:/srv/tftp/ubuntu# tree /srv/tftp//srv/tftp/└── ubuntu ├── firmware.sq ├── initrd ├── ldlinux.c32 ├── libcom32.c32 ├── libutil.c32 ├── menu.c32 ├── pxelinux.bin ├── pxelinux.cfg │ └── default ├── vesamenu.c32 └── vmlinuz
Bootloader config:
引导程序配置：
root@debian:/srv/tftp/ubuntu# cat /srv/tftp/ubuntu/pxelinux.cfg/default ui menu.c32timeout 30default ubuntu_pxe font UniCyr_8x16.psfmenu title PXE Special Boot Menumenu color tabmsg 37;40 #80ffffff #00000000menu color hotsel 30;47 #40000000 #20ffffffmenu color sel 30;47 #40000000 #20ffffffmenu color scrollbar 30;47 #40000000 #20ffffffLABEL ubuntu_pxemenu label Run ubuntu pxe kernel vmlinuz append initrd=initrd rooturl=http://192.168.56.2/ubuntu/firmware.sq boot=pxe maxTryCount=10
It’s impotant to set the correct kernel parameters:
设置正确的内核参数很重要：
rooturl=, url for rootfs
rooturl = 网址
And the last one is the dhcp config:
最后一个是dhcp配置：
root@debian:/srv/tftp/ubuntu# cat /etc/dhcp/dhcpd.confsubnet 192.168.56.0 netmask 255.255.255.0 { range 192.168.56.10 192.168.56.45; option routers 192.168.56.2; option domain-name-servers 192.168.2.1 ; option broadcast-address 192.168.56.255; default-lease-time 3600; max-lease-time 7200; # Important! Set bootloader file filename "ubuntu/pxelinux.bin"; } The extended variant (if the dhcp and tftp servers placed on different machines) requires the next-server option for dhcp.
扩展版本(如果dhcp和tftp服务器位于不同的计算机上)需要dhcp的next-server选项。
This article shows you how to change the boot mode of ubuntu without any difficulties. Use it as information and write your solutions. This can be a system in the form of firmware (with squashfs), pxe, or another solution.
本文向您展示如何轻松地更改ubuntu的启动模式。 将其用作信息并编写解决方案。 这可以是固件(带有squashfs)，pxe或其他解决方案形式的系统。
翻译自:
pxe无盘启动
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