Episode Details

We read the FreeBSD Q3 status report, explore good and bad syscalls, list GOG Games for OpenBSD, and show you what devmatch can do.

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FreeBSD Q3 Status Report 2017

• FreeBSD Team Reports
  • FreeBSD Release Engineering Team
  • Ports Collection
  • The FreeBSD Core Team
  • The FreeBSD Foundation
• Projects
  • FreeBSD CI
• Kernel
  • Intel 10G iflib Driver Update
  • Intel iWARP Support
  • pNFS Server Plan B
• Architectures
  • AMD Zen (family 17h) support
• Userland Programs
  • Updates to GDB
• Ports
  • FreeBSDDesktop
  • OpenJFX 8
  • Puppet
• Documentation
  • Absolute FreeBSD, 3rd Edition
  • Manual Pages
• Third-Party Projects
  • The nosh Project ####FreeBSD Foundation Q4 Update *** ###11 syscalls that rock the world
• 0. read > You cannot go wrong with a read. You can barely EFAULT it! On Linux amd64 it is syscall zero. If all its arguments are zero it returns zero. Cool!
• 1. pipe > The society for the preservation of historic calling conventions is very fond of pipe, as in many operating systems and architectures it preserves the fun feature of returning both of the file descriptors as return values. At least Linux MIPS does, and NetBSD does even on x86 and amd64. Multiple return values are making a comeback in languages like Lua and Go, but C has always had a bit of a funny thing about them, but they have long been supported in many calling conventions, so let us use them in syscalls! Well, one syscall.
• 2. kqueue > When the world went all C10K on our ass, and scaleable polling was a thing, Linux went epoll, the BSDs went kqueue and Solaris went /dev/poll. The nicest interface was kqueue, while epoll is some mix of edge and level triggered semantics and design errors so bugs are still being found.
• 3. unshare > Sounds like a selfish syscall, but this generous syscall call is the basis of Linux namespaces, allowing a process to isolate its resources. Containers are built from unshares.
• 4. setns > If you liked unshare, its younger but cooler friend takes file descriptors for namespaces. Pass it down a unix socket to another process, or stash it for later, and do that namespace switching. All the best system calls take file descriptors.
• 5. execveat > Despite its somewhat confusing name (FreeBSD has the saner fexecve, but other BSDs do not have support last time I checked), this syscall finally lets you execute a program just given a file descriptor for the file. I say finally, as Linux only implemented this in 3.19, which means it is hard to rely on it (yeah, stop using those stupid old kernels folks). Before that Glibc had a terrible userspace implementation that is basically useless. Perfect for creating sandboxes, as you can sandbox a program into a filesystem with nothing at all in, or with a totally controlled tree, by opening the file to execute before chroot or changing the namespace.
• 6. pdfork > Too cool