bcc VS linux

Nice - I normally use [bash-readline](https://github.com/iovisor/bcc/blob/master/tools/bashreadlin...) when coworking/co-inhabiting a server or training someone.

One of the big wins is not so much “build and run your own stuff” but there are very nice low-cost (in terms of compute) performance utilities built on eBPF

https://github.com/iovisor/bcc

There are so many utilities in that list; there’s a diagram midway down the readme which tries to help show their uses. bcc-tools should be available in any distro.

Also, Brendan Gregg does a ton of performance stuff that is worth knowing about if you check out his other work. Not eBPF only. Flame graphs are useful.

Reference: https://github.com/iovisor/bcc/blob/master/libbpf-tools/memleak.c

In this article, we'll build a basic version of an HTTPS sniffer, inspired by bcc-sslsniff.py, but we'll use Rust and Aya. We're going to demonstrate the capabilities of uprobes by employing uprobe and uretprobe along with familiar maps like PerCpuArray, HashMap, and PerEventArray. This will be a straightforward example to help us explore how uprobes function.

As xpd program I am using the BCC example xdp_redirect_map.py in skb mode as my NIC does not support native mode, attaching the program to veth2 and a dummy function to veth3

https://github.com/iovisor/bcc/blob/master/docs/reference_gu...

In Linux you can use eBPF. See https://github.com/iovisor/bcc for an easy way to write eBPF, or look for something in the tools/ dir that does what you want. You distro might have these packaged in bcc-tools or similar.

These are a bit easier to see what's going on:

https://github.com/torvalds/linux/commit/d5cf50dafc9dd5faa1e...

https://github.com/torvalds/linux/blob/d5cf50dafc9dd5faa1e61...

Unfortunately Github doesn't have a way to render symbols for whitespace, but you can tell by selecting the spaces that the previous version had leading tabs. Linus changed it so that the tokens `default` and the number e.g. `12` are also separated by a tab. This is tricky, because the token "default" is seven characters, it will always give this added tab a width of 1 char which makes it always layout the same as if it were a space no matter if you use tab widths of 1, 2, 4, or 8.

There was also a Gentoo effort to run atop FreeBSD[0]. The challenge of course is that afaik none of the BSD kernel ABIs are considered stable. The stable interface is the BSD libc. That said, with binfmt_misc, I don't see a reason you couldn't just run (at least some) FreeBSD binaries on Linux with a thin syscall translation layer (rather something like qemu-system) and then your layer hooked via binfmt_misc. I'm not aware of anyone who has done this for FreeBSD, but prior efforts existed as alternate binfmts for SysVr4/5 ELF binaries[2]. Either way would take some elbow grease, but you *might* even be able just reuse binfmt_elf and just have a new interpreter for FreeBSD elf.

[0] https://wiki.gentoo.org/wiki/Gentoo_FreeBSD

[1] https://docs.kernel.org/admin-guide/binfmt-misc.html

[2] https://github.com/torvalds/linux/blob/master/fs/binfmt_elf....

> The original less-than check was deemed incorrect

It was only deemed incorrect because of an information leak. Not because it's a valid use-case for user space to copy smaller portions of *hwrpb into user space. https://github.com/torvalds/linux/commit/21c5977a836e399fc71...

Correct. And the combined work needs to carry the MIT license text and copyright attributions for the MIT software authors. With binary distribution it must also be overt, not hidden in some source code drop, but directly accompanying the binary.

Many people who talk about relicensing never credit the MIT developers or distribute the MIT license text. "Because it's GPL now."

I don't think that you believe that, but many developers do.

Some don't see the need for source code scans for Open Source compliance, because the license.txt says GPL, so it's GPL. Prime example is the Linux kernel. There is code under different licenses in there, but people don't even read https://github.com/torvalds/linux/blob/master/COPYING till the end ("In addition, other licenses may also apply.") and conclude it's simply GPL 2 and nothing else.

Also be aware that sublicensing is not the same as relicensing.

> Does he have something against it?

He notoriously hates GNU Emacs, yes.

https://marc.info/?m=122955159617722

https://github.com/torvalds/linux/blob/master/Documentation/...

So If we would only count code and not comments, it is only 9489 LoC Rust. Which would be about 0.03% and if we take all lines and not only LoC it would be around 0.05%

[0] https://github.com/XAMPPRocky/tokei

[1] https://github.com/torvalds/linux/commit/b401b621758e46812da...

AIUI fsync is built on futex_waitv which has been upstreamed. So this has to be more than that.

https://github.com/torvalds/linux/commit/a0eb2da92b715d0c97b...

git clone --no-checkout --depth 1 https://github.com/torvalds/linux.git $dir