Compile issue: "invalid relo against 'nr_latches'" about ghost-userspace HOT 7 CLOSED

probably due to a change in libbpf. perhaps you're using a newer one than we are. i see other some commits in libbpf-tools zero-initializing globals.

the fix would be to zero initialize the globals in all of our tools.

from ghost-userspace.

Thanks, I'll take a look tomorrow. If it turns out the zero-initialization isn't guaranteed by the standard, then I'll push a commit to fix this. Otherwise I'll figure out what the real issue is and post here.

from ghost-userspace.

Hello,
me I have meet this error and to solve this problem, I have just initialize some variable in
the following file : third_party/bpf/schedghostidle.bpf.c.
In that file I have just initialize the following variable:
uint64_t nr_latches = 0;
uint64_t nr_bpf_latches = 0;
uint64_t nr_idle_to_bpf_latches = 0;
Try to do it and we will see if it work on your project.

from ghost-userspace.

@NGUETOUM Thanks so much!
It solved the compile problem. Just not sure whether those variables should be initialized to specific values. I am going to try some example benchmark to see what will happen:)

from ghost-userspace.

@john-liu2039 They should be initialized to 0. I need to look into why this is causing compile issues on your end since the global variables should be zero-initialized by default just as they would be in a userspace program. What version of clang are you using?

from ghost-userspace.

Thanks, @jackhumphries :) My clang setup is as follows:

clang version 10.0.0-4ubuntu1 
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

BTW, I set up the ghost kernel and userspace with the VMware virtual machine.
Thanks so much for your help!

from ghost-userspace.

Thanks Barret.

I have explicitly initialized the BPF global variables to 0 in our internal Google codebase. This will make its way out to the open source codebase soon.

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