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I am trying to install a Linux kernel (3.8.1) from source in a Fedora distribution. The kernel is a vanilla one. I follow the kernel's build instructions closely that is:

make menuconfig make sudo make modules_install install sudo grub2-mkconfig -o /boot/grub2/grub.cfg

Everything in /boot seems fine. I can see System.map, initramfs, and vmlinuz for the newly compiled kernel. The vmlinuz link points to vmlinuz-3.8.1. There are multiple other kernels installed including an Ubuntu one. grub2 recognises all of them and I can boot to each one of them.

When I reboot I see all kernels as menu entries and choose 3.8.1.

Then I see this message:

early console in decompress_kernel decompressing Linux... parsing ELF ... done Booting the kernel. [1.687084] systemd [1]:failed to mount /dev:no such device [1.687524] systemd [1]:failed to mount /dev:no such device

Solution:

All three posted responses provide the solution. CONFIG_DEVTMPFS was in fact causing the issue. I copied a working kernel's /boot/config-… into the root of the source tree as .config and executed the standard commands for building the kernel also shown above.

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    Why are you building such an old kernel, BTW? Commented Feb 25, 2014 at 16:24
  • It depends on one's own definition of old. I, for example, would consider v2.6 old :-). I am doing some tests on kernel data structures for research purposes. This version was at my hand's reach, but many others would do just fine. Commented Feb 26, 2014 at 18:34

3 Answers 3

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You need to configure your kernel with these options:

Linux kernel >= 3.0 CONFIG_DEVTMPFS CONFIG_CGROUPS (it's OK to disable all controllers) CONFIG_INOTIFY_USER CONFIG_SIGNALFD CONFIG_TIMERFD CONFIG_EPOLL CONFIG_NET CONFIG_SYSFS CONFIG_PROC_FS CONFIG_FHANDLE (libudev, mount and bind mount handling) Linux kernel >= 3.8 for Smack support Udev will fail to work with the legacy layout: CONFIG_SYSFS_DEPRECATED=n Legacy hotplug slows down the system and confuses udev: CONFIG_UEVENT_HELPER_PATH="" Userspace firmware loading is deprecated, will go away, and sometimes causes problems: CONFIG_FW_LOADER_USER_HELPER=n Some udev rules and virtualization detection relies on it: CONFIG_DMIID Support for some SCSI devices serial number retrieval, to create additional symlinks in /dev/disk/ and /dev/tape: CONFIG_BLK_DEV_BSG Optional but strongly recommended: CONFIG_IPV6 CONFIG_AUTOFS4_FS CONFIG_TMPFS_POSIX_ACL CONFIG_TMPFS_XATTR CONFIG_SECCOMP For systemd-bootchart, several proc debug interfaces are required: CONFIG_SCHEDSTATS CONFIG_SCHED_DEBUG For UEFI systems: CONFIG_EFI_VARS CONFIG_EFI_PARTITION Note that kernel auditing is broken when used with systemd's container code. When using systemd in conjunction with containers, please make sure to either turn off auditing at runtime using the kernel command line option "audit=0", or turn it off at kernel compile time using: CONFIG_AUDIT=n
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Easiest way to get a working kernel configuration is to just copy Fedora's .config over and then do a make oldconfig to configure it. The configuration is found at /boot/config-*

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Looking at a similar issue on a custom system running systemd it seems this may be because "CONFIG_DEVTMPFS" is not selected in the kernel configuration (notice this is the first thing on sciurus's list of kernel requirements for running systemd).

To now figure out how to correct this, start make menuconfig and use the search feature (press /) to look for "DEVTMPFS". The first hit is:

Symbol: DEVTMPFS [=y] Type : boolean Prompt: Maintain a devtmpfs filesystem to mount at /dev Location: -> Device Drivers (1) -> Generic Driver Options

Low and behold, there is such an option in Device Drivers->Generic Driver Options.

As vonbrand says, you are best off starting with a configuration that matches what you have now. This can probably be found gzipped as /proc/config.gz. Copy that out and gunzip -c config.gz > .config and use that file as the preliminary .config in your source tree (more detail in step #2 here).

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