Subject: Re: linux-next: build failure after merge of the perf tree

From: Stephen Rothwell <[email-masked]>
Date: Tue, 28 Mar 2023 12:33:32 +1100

Hi Arnaldo,

Just a few datapoints:

My build machine (Debian Testing PowerpcLE, not quite the latest
kernel):

On Thu, 23 Mar 2023 10:27:36 -0300 Arnaldo Carvalho de Melo <[email-masked]> wrote:
>  Which improves a bit the situation.
> 
> We could check if bpftool is available and if not, suggest installing
> it.

$ ls -l /usr/sbin/bpftool
-rwxr-xr-x 1 root root 790504 Mar  6 02:33 /usr/sbin/bpftool

> If it is available, we could check if /sys/kernel/bpf/ is available, if
> not suggest using a kernel with CONFIG_DEBUG_INFO_BTF=y, as most distros
> have by now.

$ uname -a
Linux zz1 6.0.0-5-powerpc64le #1 SMP Debian 6.0.10-2 (2022-12-01) ppc64le GNU/Linux
$ ls -l /sys/kernel/bpf/
ls: cannot access '/sys/kernel/bpf/': No such file or directory
$ grep CONFIG_DEBUG_INFO_BTF /boot/config-6.0.0-5-powerpc64le
# CONFIG_DEBUG_INFO_BTF is not set

And in the latest powerpc64le kernel:

$ grep CONFIG_DEBUG_INFO_BTF /boot/config-6.1.0-5-powerpc64le
# CONFIG_DEBUG_INFO_BTF is not set

Debian Testing arm64, not quite the latest kernel:

$ uname -a
Linux oak 6.1.0-5-arm64 #1 SMP Debian 6.1.12-1 (2023-02-15) aarch64 GNU/Linux
$ ls -l /sys/kernel/bpf/
ls: cannot access '/sys/kernel/bpf/': No such file or directory
$ grep CONFIG_DEBUG_INFO_BTF /boot/config-6.1.0-5-arm64
CONFIG_DEBUG_INFO_BTF=y
CONFIG_DEBUG_INFO_BTF_MODULES=y

Debian Testing amd64, the latest kernel:

$ uname -a
Linux pine 6.1.0-6-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.15-1 (2023-03-05) x86_64 GNU/Linux
$ ls -l /sys/kernel/bpf/
ls: cannot access '/sys/kernel/bpf/': No such file or directory
$ grep CONFIG_DEBUG_INFO_BTF /boot/config-6.1.0-6-amd64
CONFIG_DEBUG_INFO_BTF=y
CONFIG_DEBUG_INFO_BTF_MODULES=y

Debian Stable amd64, the latest kernel:

$ uname -a
Linux gimli 5.10.0-21-cloud-amd64 #1 SMP Debian 5.10.162-1 (2023-01-21) x86_64 GNU/Linux
$ ls -l /sys/kernel/bpf/
ls: cannot access '/sys/kernel/bpf/': No such file or directory
$ grep CONFIG_DEBUG_INFO_BTF /boot/config-5.10.0-21-cloud-amd64
CONFIG_DEBUG_INFO_BTF=y

-- 
Cheers,
Stephen Rothwell