Trying to compile a kernel results in "FAILED: load BTF from vmlinux: No such file or directory"

[ReneNyffenegger]

Windows Version

Microsoft Windows [Version 10.0.22621.1992]

WSL Version

1.2.5.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

Linux version 5.15.90.1-microsoft-standard-WSL2

Distro Version

Debian 11 (lsb_release is not available as command)

Other Software

No response

Repro Steps

git clone https://github.com/microsoft/WSL2-Linux-Kernel
cd WSL2-Linux-Kernel
cp Microsoft/config-wsl .config
make -j 4

Expected Behavior

The kernel would be built

Actual Behavior

The build process ends with the error message

FAILED: load BTF from vmlinux: No such file or directory

Diagnostic Logs

No response

[OneBlue]

Thank you for reporting this @ReneNyffenegger. Do you see the same error by following the build instructions ?

$ sudo apt install build-essential flex bison dwarves libssl-dev libelf-dev
$ make KCONFIG_CONFIG=Microsoft/config-wsl

?

[ReneNyffenegger]

It turned out I had quite a few packages not installed: flex, bison, dwarves, libssl-dev and libelf-dev.

After installing them with the proposed sudo apt install... command and building it with make KCONFIG..., I got

/bin/sh: 1: bc: not found

after also nstalleding bc ...

sudo apt install -y bc

... the build went on without further problems (I did not yet try to install the new built kernel)

[OneBlue]

Nice ! Thank you for confirming.

Closing since the issue is resolved.

[okineadev]

I found the cause of the problem on Stack Exchange - https://unix.stackexchange.com/a/616479/608997

I ran into the same issue today, for me the issue was that pahole ran out of memory (peak memory usage of pahole was around 2.5GB).

In order to solve this problem, I removed the RAM limit in .wslconfig:

[wsl2]
# memory=3GB

After that I compiled the WSL kernel without any problems

You can learn more about .wslconfig and memory limits at this link- https://learn.microsoft.com/en-us/windows/wsl/wsl-config#main-wsl-settings