红帽全球峰会3.2. Systems with legacy BIOS firmware
The boot/grub2/grub.cfg configuration file on the boot media contains a list of preconfigured menu entries and other directives which controls the appearance and the Boot menu functionality. In the configuration file, the default menu entry for Red Hat Enterprise Linux (Test this media & install Red Hat Enterprise Linux 10) is defined in the following block:
menuentry 'Install Red Hat Enterprise Linux 10.0' --class fedora --class gnu-linux --class gnu --class os {
linux /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=RHEL-10-0-BaseOS-x86_64 quiet
initrd /images/pxeboot/initrd.img
}
menuentry 'Test this media & install Red Hat Enterprise Linux 10.0' --class fedora --class gnu-linux --class gnu --class os {
linux /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=RHEL-10-0-BaseOS-x86_64 rd.live.check quiet
initrd /images/pxeboot/initrd.img
}Where:
menuentry- Defines the title of the entry. It is specified in single or double quotes (' or "). You can use the--classoption to group menu entries into different classes, which can then be styled differently using GRUB2 themes.注意You must enclose each menu entry definition in curly braces ({}).
linux- Defines the kernel that boots (/images/pxeboot/vmlinuzin the example) and the other additional options, if any. You can customize these options to change the behavior of the boot entry. For details about the options that are applicable to Anaconda, see Automatically installing RHEL. One of the notable options isinst.ks=that allows you to specify a location of a Kickstart file. You can place a Kickstart file on the boot ISO image and use theinst.ks=option to specify its location; for example, you can place akickstart.ksfile into the image’s root directory and useinst.ks=hd:LABEL=RHEL-10-0-BaseOS-x86_64:/kickstart.ks. You can also use dracut options which are listed on thedracut.cmdline(7)man page.重要When using a disk label to refer to a certain drive, for example,
inst.stage2=hd:LABEL=RHEL-10-0-BaseOS-x86_64, replace all spaces with\x20.initrd- Location of the initial RAM disk (initrd) image to be loaded. Other options used in thegrub.cfgconfiguration file are:set timeout- determines how long is the boot menu displayed before the default menu entry is automatically used. The default value is 60, which means the menu is displayed for 60 seconds. Setting this value to-1disables the timeout completely.注意Setting the timeout to 0 is useful when performing a headless installation, because this setting immediately activates the default boot entry.
submenu- A submenu block allows you to create a sub-menu and group some entries under it, instead of displaying them in the main menu. The Troubleshooting submenu in the default configuration contains entries for rescuing an existing system. The title of the entry is in single or double quotes (' or "). The submenu block contains one or more menuentry definitions as described above, and the entire block is enclosed in curly braces ({}). For example:submenu 'Submenu title' { menuentry 'Submenu option 1' { linux /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=RHEL-10-0-BaseOS-x86_64 nomodeset quiet initrd /images/pxeboot/initrd.img } menuentry 'Submenu option 2' { linux /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=RHEL-10-0-BaseOS-x86_64 inst.rescue quiet initrd /images/pxeboot/initrd.img } }-
set default- Determines the default entry. The entry numbers start from 0. If you want to make the third entry the default one, use setdefault=2and so on. -
theme- Determines the directory which contains GRUB2 theme files. You can use the themes to customize visual aspects of the boot loader - background, fonts, and colors of specific elements.
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