Hacker News: khrbtxyz

New comment by khrbtxyz in "A 32-year-old bug walks into a Telnet server"

khrbtxyz — Thu, 17 Sep 2026 05:52:24 +0000

A surprisingly long article for a one-line fix the authors didn’t send.

New comment by khrbtxyz in "OpenBSD has a use-after-free allowing local privilege escalation to root"

khrbtxyz — Thu, 09 Jul 2026 23:06:16 +0000

It is required mainly for VMs that use virbr0 and NAT. Networking options like macvtap don't need it.

New comment by khrbtxyz in "How to create an OS from scratch"

khrbtxyz — Tue, 30 Sep 2025 03:49:45 +0000

https://github.com/mariuz/linux-0.01 might give you some ideas.

New comment by khrbtxyz in "Atomics and Concurrency"

khrbtxyz — Fri, 30 May 2025 16:18:18 +0000

https://en.wikipedia.org/wiki/Load-link/store-conditional

New comment by khrbtxyz in "Path Isn't Real on Linux"

khrbtxyz — Wed, 30 Apr 2025 01:32:45 +0000

Another bit of trivia about the shebang support in Linux is that is possible to build the kernel without it. https://github.com/torvalds/linux/blob/master/fs/Kconfig.bin...

  config BINFMT_SCRIPT
  tristate "Kernel support for scripts starting with #!"
  default y
  help
    Say Y here if you want to execute interpreted scripts starting with
    #! followed by the path to an interpreter.

New comment by khrbtxyz in "Landrun: Sandbox any Linux process using Landlock, no root or containers"

khrbtxyz — Sun, 23 Mar 2025 00:24:36 +0000

I don't quite understand what --exec does. If I leave out --exec from example 3, is it supposed to prevent bash from executing other programs?

  $ landrun --log-level debug --ro /usr/bin,/lib,/lib64 /usr/bin/bash --norc
  [landrun] 2025/03/22 17:16:29 Sandbox config: {ReadOnlyPaths:[/usr/bin /lib /lib64] ReadWritePaths:[] AllowExec:false BindTCPPorts:[] ConnectTCPPorts:[] BestEffort:true}
  [landrun:debug] 2025/03/22 17:16:29 Adding read-only path: /usr/bin
  [landrun:debug] 2025/03/22 17:16:29 Adding read-only path: /lib
  [landrun:debug] 2025/03/22 17:16:29 Adding read-only path: /lib64
  [landrun:debug] 2025/03/22 17:16:29 Applying Landlock restrictions
  [landrun] 2025/03/22 17:16:29 Landlock restrictions applied successfully
  [landrun] 2025/03/22 17:16:29 Executing: [/usr/bin/bash --norc]
  bash-5.2$ 
  bash-5.2$ /usr/bin/uname -r
  6.13.7-200.fc41.aarch64

New comment by khrbtxyz in "Everything You Never Wanted to Know About Linker Script (2021)"

khrbtxyz — Sat, 30 Nov 2024 17:01:11 +0000

Large projects like the Linux kernel, which are mostly C, use the preprocessor in .S files quite heavily.

Linux has hardly any .s files.

  ~/linux$ find . -name '*.s'
  ./arch/x86/kernel/asm-offsets.s
  ./kernel/bounds.s
  ./scripts/mod/devicetable-offsets.s

But there are plenty of .S files with #includes

  ~/linux$ $ find . -name '*.S' | xargs grep -l '#include' | wc -l
  1217

Edit: simplify command as suggested

New comment by khrbtxyz in "C Gibberish to English"

khrbtxyz — Thu, 14 Nov 2024 15:18:09 +0000

Function typedefs make this less confusing by removing awkward parentheses. e.g.

  typedef int read_block_fn(void *context, u8 *buf, unsigned int block, size_t len);

https://github.com/torvalds/linux/blob/0a9b9d17f3a781dea03ba...

New comment by khrbtxyz in "M4 MacBook Pro"

khrbtxyz — Thu, 31 Oct 2024 02:08:17 +0000

Nested virtualization needs at least an M3

https://developer.apple.com/documentation/virtualization/vzg...

This is the sad situation on my M2 MacBook Pro :(

  $ swift repl
  Welcome to Apple Swift version 6.0.2 (swiftlang-6.0.2.1.2 clang-1600.0.26.4).
  Type :help for assistance.
    1> import Virtualization
    2> VZGenericPlatformConfiguration.isNestedVirtualizationSupported
  $R0: Bool = false

New comment by khrbtxyz in "New iMac with M4"

khrbtxyz — Mon, 28 Oct 2024 17:36:41 +0000

This is form-over-function, classic Apple. They don't want to give even the slightest impression that they are selling a wired mouse.

New comment by khrbtxyz in "Exploring How Cache Memory Works"

khrbtxyz — Thu, 27 Jun 2024 07:38:02 +0000

From a Raspberry Pi 5: L2 cache line is 128

  Vendor ID:              ARM
  Model name:             Cortex-A76

  $ lscpu -C
  NAME ONE-SIZE ALL-SIZE WAYS TYPE        LEVEL SETS PHY-LINE COHERENCY-SIZE
  L1d       64K     256K    4 Data            1  256                      64
  L1i       64K     256K    4 Instruction     1  256                      64
  L2       512K       2M    4 Unified         2 1024                     128
  L3         2M       2M   16 Unified         3 2048                      64

New comment by khrbtxyz in "Daily Automated Testing for Milk-V Duo S RISC-V SBC (IKEA Tretakt, Apache NuttX)"

khrbtxyz — Sun, 23 Jun 2024 04:45:26 +0000

There's a Python library that has been quite reliable for me for local control.

  $ python3
  Python 3.12.4 (main, Jun  6 2024, 18:26:44) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  >>> import pywemo
  >>> d = pywemo.discover_devices()
  >>> d
  [, , ]
  >>> d[0].model
  'Belkin Plugin Socket 1.0'
  >>> d[0].toggle()
  >>>

New comment by khrbtxyz in "EasyOS: An experimental Linux distribution"

khrbtxyz — Thu, 20 Jun 2024 05:14:54 +0000

Yes, these commands have way too many options for anyone to remember. The commands are best wrapped up in a script. An ISO install is usually a manual process that can take time, but it is definitely easier.

New comment by khrbtxyz in "EasyOS: An experimental Linux distribution"

khrbtxyz — Wed, 19 Jun 2024 23:41:06 +0000

Most Linux distributions ship ready-made VM images which are easier to turn into VMs. See https://news.ycombinator.com/item?id=40610332

New comment by khrbtxyz in "Off-path TCP hijacking in NAT-enabled Wi-Fi networks"

khrbtxyz — Wed, 19 Jun 2024 02:16:44 +0000

https://www.apple.com/shop/product/HMJU2ZM/A/belkin-ethernet...

New comment by khrbtxyz in "Hello world in C inline assembly (2018)"

khrbtxyz — Mon, 17 Jun 2024 08:47:34 +0000

The exact same thing happens with GCC 12 with 32-bit MIPS.

  #include 
   
  char msg[] = "hello, world!\n";
   
  int main(void)
  {
      register int syscall_no asm("v0") = __NR_write;
      register int arg1       asm("a0") = 1;
      register char *arg2     asm("a1") = msg;
      register int arg3       asm("a2") = sizeof(msg) - 1;
   
      asm("syscall");
   
      return 0;
  }

  root@OpenWrt:~# objdump --disassemble=main
  ...
  00400580 :
    400580: 27bdfff8  addiu sp,sp,-8
    400584: afbe0004  sw s8,4(sp)
    400588: 03a0f025  move s8,sp
    40058c: 24020fa4  li v0,4004
    400590: 24040001  li a0,1
    400594: 3c020041  lui v0,0x41
    400598: 24450650  addiu a1,v0,1616
    40059c: 2406000e  li a2,14
    4005a0: 0000000c  syscall

New comment by khrbtxyz in "Understanding QEMU Devices (2018)"

khrbtxyz — Fri, 07 Jun 2024 16:39:45 +0000

There's also virt-install, which is part of the Virt Manager package. https://github.com/virt-manager/virt-manager/blob/main/man/v...

  curl --output-dir $HOME/.local/share/libvirt/images/ -LO https://cloud.debian.org/images/cloud/bookworm/20240507-1740/debian-12-genericcloud-arm64-20240507-1740.qcow2
  virt-install --import --osinfo debian12 --disk size=20,backing_store=$HOME/.local/share/libvirt/images/debian-12-genericcloud-arm64-20240507-1740.qcow2 --controller type=scsi,model=virtio-scsi --cloud-init

New comment by khrbtxyz in "Show HN: A Short IPv6 Guide for Home IPv4 Admins"

khrbtxyz — Fri, 07 Jun 2024 01:32:07 +0000

Returning both the ULA and global addresses should be okay. This is what my OpenWRT router does without any special setup. wk1 is one of my local machines.

  $ dig +short wk1 AAAA @192.168.1.1
  2601:646:...
  fd7c:b0fd:fd6a:1::ba5

New comment by khrbtxyz in "Ask HN: What are your favourite programming shortcuts"

khrbtxyz — Sat, 30 Mar 2024 07:46:02 +0000

Found it in the readline manual

https://tiswww.cwru.edu/php/chet/readline/readline.html#inde...

insert-comment (M-#) Without a numeric argument, the value of the comment-begin variable is inserted at the beginning of the current line.

New comment by khrbtxyz in "Ask HN: What are your favourite programming shortcuts"

khrbtxyz — Sat, 30 Mar 2024 04:06:00 +0000

Is this something special you have set up on your Mac?

I keep getting screenshots when I hit command-shift-3. https://support.apple.com/en-us/102646