3 ms·

Cool! Very interesting development given how bad reputation microkernels had for a while. (I’m thinking of Linux vs Minix/Hurd.)

by cpach 5y ago

kzrdude 5y ago
macOS (Mac OS X lineage) was always based on mach (a microkernel) which made it a hybrid kernel: https://en.wikipedia.org/wiki/XNU https://en.wikipedia.org/wiki/XNU
zibzab 5y ago
FYI, Linux userspace drivers were introduced in 2006-2007 and improved multiple times over the years. Some of my filesystem & networking drivers run in usersapce. The monolithic vs microkernel debate was pretty clueless at times. Core Linux is smaller than dito hurd when configured with similar functionality. OSX mach has always been a hybrid kernel. In a sense Linux is too but you can also configure it as a mostly-monolithic thing, and most seem to prefer that.
- creshal 5y ago
  Some of the userspace drivers are even shared between OSX and Linux, via FUSE.
  - roblabla 5y ago
    Another example would be userspace network drivers that directly talk to the network card. Those tend to be much more performant than using the kernel driver due to avoiding the need to context switch from userspace to kernelspace.
    - zibzab 5y ago
      Is that really true in pratice (excluding unikernels, of course)?
    - MayeulC 5y ago
      Aren't we making userspace/kernel space communication a lot more efficient with io-uring, though? Likewise, eBPF allows userspace programs to perform some work inside kernel space to reduce syscalls. I wonder if io-uring won't be a starting point for a "microkernelization" of Linux. It seems really effective as a message-passing interface.
      - pjmlp 5y ago
        Look at Android' Project Treble, that is what Google has done, just with Android IPC instead of io-uring.
pjmlp 5y ago
Since Android 8, Linux is a kind of pseudo-microkernel, as all drivers are required to be Treble based, and traditional Linux drivers are considered legacy on the platform. https://source.android.com/devices/architecture/hal-types https://source.android.com/devices/architecture/hal-types The Switch (yes the games console) uses a microkernel. QNX an OS for human critical scenarios is a microkernel. Finally, when arguing Linux vs Minix/Hurd, think of the irony of running Linux on top of a cloud hypervisor, with an endless load of Kubernetes or Docker loads.
- SlowRobotAhead 5y ago
  > QNX an OS for human critical scenarios is a microkernel. Hmm, Never thought about a stated OS focus like that. Off to look it up. Good mention
  - pjmlp 5y ago
    Search for high integrity computing, that is the industry term.
tzs 5y ago
At the time of the Linux vs. Minix debate, on pretty much every performance measure that Linus said monolithic kernels were better at the microkernel QNX was totally wiping the floor with Linux.

Cool! Very interesting development given how bad reputation microkernels had for a while. (I’m thinking of Linux vs Minix/Hurd.)

by cpach 5y ago

Cool! Very interesting development given how bad reputation microkernels had for a while. (I’m thinking of Linux vs Minix/Hurd.)

kzrdude 5y ago

macOS (Mac OS X lineage) was always based on mach (a microkernel) which made it a hybrid kernel: https://en.wikipedia.org/wiki/XNU https://en.wikipedia.org/wiki/XNU

zibzab 5y ago

FYI, Linux userspace drivers were introduced in 2006-2007 and improved multiple times over the years. Some of my filesystem & networking drivers run in usersapce. The monolithic vs microkernel debate was pretty clueless at times. Core Linux is smaller than dito hurd when configured with similar functionality. OSX mach has always been a hybrid kernel. In a sense Linux is too but you can also configure it as a mostly-monolithic thing, and most seem to prefer that.

creshal 5y ago
Some of the userspace drivers are even shared between OSX and Linux, via FUSE.
- roblabla 5y ago
  Another example would be userspace network drivers that directly talk to the network card. Those tend to be much more performant than using the kernel driver due to avoiding the need to context switch from userspace to kernelspace.
  - zibzab 5y ago
    Is that really true in pratice (excluding unikernels, of course)?
  - MayeulC 5y ago
    Aren't we making userspace/kernel space communication a lot more efficient with io-uring, though? Likewise, eBPF allows userspace programs to perform some work inside kernel space to reduce syscalls. I wonder if io-uring won't be a starting point for a "microkernelization" of Linux. It seems really effective as a message-passing interface.
    - pjmlp 5y ago
      Look at Android' Project Treble, that is what Google has done, just with Android IPC instead of io-uring.

pjmlp 5y ago

Since Android 8, Linux is a kind of pseudo-microkernel, as all drivers are required to be Treble based, and traditional Linux drivers are considered legacy on the platform. https://source.android.com/devices/architecture/hal-types https://source.android.com/devices/architecture/hal-types The Switch (yes the games console) uses a microkernel. QNX an OS for human critical scenarios is a microkernel. Finally, when arguing Linux vs Minix/Hurd, think of the irony of running Linux on top of a cloud hypervisor, with an endless load of Kubernetes or Docker loads.

SlowRobotAhead 5y ago
> QNX an OS for human critical scenarios is a microkernel. Hmm, Never thought about a stated OS focus like that. Off to look it up. Good mention
- pjmlp 5y ago
  Search for high integrity computing, that is the industry term.

tzs 5y ago

At the time of the Linux vs. Minix debate, on pretty much every performance measure that Linus said monolithic kernels were better at the microkernel QNX was totally wiping the floor with Linux.