I use Linux kerne EFI stub to boot. Now I have run into an emergency, because I have lost my UEFI boot entry and I am stuck with Windows.
Is there any possibility to create UEFI NVRAM boot entry for Linux kernel?
I have managed to create it, but without kernel args (like: root=PARTUUID=....) and Linux is not booting without them.
Is there a way how to create boot menu entry from Windows 10 with CLI args?
One solution could be:
Mount the ESP partition under windows.
Create a startup.nsh script to pass kernel parameters
Create boot menu entry which points to the startup.nsh
One way you can resolve this:
You can run any live linux OS, chroot to your still existing installed Linux Distribution, and reinstall grub, which will re-add Linux to the boot menu alongside Windows.
Related
I have a linux built with a buildroot for a Beaglebone wireless board. In the root file system, when it is still on the host and has not been copied to the target, in the /dev folder, there are device files fd, log, stderr, stdin, stdout only. When I load this root file system on the target and launch the target, there are many more devices - many tty, zero, urandom etc. They are created during the Linux boot process. Buildroot built the system using simple busybox init program. In init scripts i do not see the process of creating device nodes, who creates this device nodes?
Your system is probably using devtmpfs. It is a pseudo filesystem that is mounted on /dev where the kernel will populate device nodes for devices it knows about.
udev relies on devtmpfs since commit 220893b3cbdb ("remove mknod() logic and rely on 'devtmpfs'") which is 9 years old now.
If your target is running busybox, you may have the mdev applet. Look at the installed applets with busybox --help.
mdev uses a configuration file: /etc/mdev.conf
I have rpi3.
This situation is under the embedded system.
The RPI reference shows how to boot Ubuntu.
It shows the way that u-boot calls grub and grub calls Linux...
and I have tried this chain loading.
In that situation, I wonder why u-boot calls grub? not directly calls Linux? Is it possible that grub calls Linux without u-boot?
GRUB requires a firmware to load it. U-Boot is one embodiment of such a firmware. For the Raspberry 3 you could use EDK2 [1] or barebox [3] instead.
Linux can be loaded directly from U-Boot. Either using the Linux EFI stub via the bootefi command or via the booti (64 bit) or bootm (32 bit) command.
Some distributions (Suse, Fedora [2]) have decided that it will make maintenance easier if all supported systems are booted in the same way, i.e. via GRUB. Debian Buster is also moving to GRUB on ARMv8 with the Buster release.
[1] https://github.com/tianocore/edk2-platforms/tree/master/Platform/RaspberryPi/RPi3
[2] https://fedoraproject.org/wiki/Changes/uEFIforARMv7
[3] https://www.barebox.org/
I had installed ubuntu 18 in my acer aspire. Then i installed windows 10 in dual boot mode. After installing the windows i can not access the ubuntu. The grub loader is not shown.
And there is no way to access my ubuntu.
I even tried to change the path of bootloader to ubuntu in cmd.
But no success. Please help me out.
check this link: https://askubuntu.com/questions/602602/cant-access-ubuntu-after-creating-dual-boot
"YOUR COMPUTER BOOTS DIRECTLY TO WINDOWS
This is a common problem and if you do not get a GRUB menu , re-installing or repairing grub will NOT HELP
Every BIOS is different, it might look like one of the following pictures:
UEFI 1
UEFI 2
Notice the "UEFI Boot Option Priority" or "Boot Option Menu" . Usually Windows is the default and Ubuntu (or as in the second picture elementary OS) will be an option.
Once you select Ubuntu on the UEFI boot menu you will then get a grub menu. You should be able to boot either Ubuntu or Windows from the grub menu.
Another issue that could make the system boot directly to Windows (without even showing the GRUB menu) is if either Windows took hold of the boot manager or after installing Ubuntu, the EFI partition was not properly configured for Windows. To solve this, simply go to Windows and open a terminal, then type the following (Need Administrative Privileges):
bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi This will configure the Windows Boot Manager to take into consideration the GRUB Boot Manager. This could still happen even after running the Boot Repair from within Ubuntu. So making sure that Windows reads the Ubuntu EFI partition will solve it."
I try to build a reproducible automated build environment based on Debian 8.1 Jessie.
I created a boot iso image based on a netinstall image and put a preseed.cfg file in int for automatic installation.
I managed to get it bootable with BIOS and UEFI and can install a KDE Developer Debian in VMWare Workstation 11 fully automated.
I have also a server iso image to install a debian Server with Jenkins, both with BIOS and UEFI Boot.
But after the installation, the Version with UEFI Boot shows a black Screen when started.
I can blindly log in, start the gui with "startx" and see my installed xfce desktop. When i quit xfce the console is usable and visible.
I tried suggested bootparameters "nomodeset" and "vga=Linux" that i found with google to no avail.
I also tried to debug the boot prozess, to find out which command leads to a blank screen, but i did not find the right place to delay the processes at bootup so i can see when the messages dissapear (quiet bootparameter was removed :-)
I also tried to reset the console to no avail.
Can anybode point me to a tool that does the same "switching" like X so the console is useable?
Can anybody give me some hints how to debug the bootprocess to find out which command is causing this behaviour?
I dont want to install X because this should be a headless server system later.
I managed to get my system to boot using the kernel command line modprobe.blacklist=vmwgfx, or placing 'blacklist vmwgfx' in /etc/modprobe.d/*.conf
I assume it is some bug in the vmwgfx module, however as this workaround works for me I have no immediate need to investigate further.
I have both windows and linux installed.
I created a new partition but got Grub error:UNKNOWN FILESYSTEM on restart. Then I used windows recovery CD and Bootrec/fixmbr command to get Grub menu back.
But now I don't see the boot menu.laptop simply boots into windows, also I am unable to boot from any other CD or USB
You need to reinstall grub on the boot sector. If you use Ubuntu, there is a very easy way to fix it with Ubuntu's live CD using the boot-repair tool.
I'm not sure if this will work with other Linux distributions but It's worth trying.
If you can't boot from CD or USB you should check your boot priority in the BIOS. Or try to get to boot selection menu (usually by pressing F12) and choose CD\USB over there, anyways, the answer here is in the BIOS and not related to the grub