RUMP KERNELS and {why,how} we got here New Directions in Operating - - PowerPoint PPT Presentation

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RUMP KERNELS and {why,how} we got here New Directions in Operating - - PowerPoint PPT Presentation

Mar 23, 2023 339 likes •698 views

RUMP KERNELS and {why,how} we got here New Directions in Operating Systems November 2014, London Antti Kantee, Fixup Software Ltd. pooka@rumpkernel.org @anttikantee Motivations want to run an application, not an OS want a better

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New Directions in Operating Systems November 2014, London Antti Kantee, Fixup Software Ltd. pooka@rumpkernel.org @anttikantee

RUMP KERNELS and {why,how} we got here

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Motivations

  • want to run an application, not an OS
  • want a better operating system
  • “operating system gets in the way”
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FIRST HALF

what is an operating system

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Summary of OS's

  • drivers

– for enabling applications to run – n*106 LoC

  • optional goop defining relation between drivers

and applications

– for protection, resource sharing, ... – 103 – 105 LoC

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kernel

driver driver driver driver driver application application

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kernel

driver driver driver application application

Server (“OS”)

driver driver

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kernel

application application

server

driver

server

driver

server

driver

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driver application

cpu core

driver application

cpu core

driver application

cpu core

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kernel

driver driver driver driver application

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kernel

driver driver driver driver driver application application

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SECOND HALF

what is a rump kernel

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platform hypercall interface

rump kernel

hypercall implementation

TCP/IP file systems device drvs syscalls

... callers (i.e. “clients”)

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rump (n):

small or inferior remnant or offshoot; especially: a group (as a parliament) carrying on in the name of the original body after the departure or expulsion

  • f a large number of its members
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rump kernel (n):

small or inferior remnant or offshoot; specifically: a monolithic OS kernel carrying on in the name of the original body after the departure or expulsion

  • f a large number of its subsystems
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A rump kernel does not provide threads, a scheduler, exec, or virtual memory, nor does it require privileged mode (or emulation of it)

  • r interrupts

> runs anywhere > integrates into other systems

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Wait, that doesn't explain where the drivers come from < anykernel (NetBSD)

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platform hypercall interface

rump kernel

hypercall implementation libc

syscall traps rump kernel calls

application(s) userspace libraries

TCP/IP file systems device drvs

unmodified NetBSD code (~106 lines) unmodified POSIX userspace code (10n lines) platform-specific code (~103 lines)

same thread throughout entire stack

e.g. Genode OS, Xen, userspace, bare-metal,

syscalls

...

Platform-independent glue code (~104 lines)

glue code

AN EXAMPLE!

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THIRD HALF

(with operating systems, expect the unexpected)

how rump kernels happened

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ad-hoc shims

Step 1: RUMP (2007)

NetBSD userspace hypercall implementation

unmodified file system driver VFS emustub rump kernel

userspace fs framework

(userspace part)

userspace kernel file system driver

userspace fs framework

(kernel part)

application

syscalls, VFS, etc.

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Step 2: UKFS (2007)

userspace kernel

Q: how hard can implementing a few syscalls be? A: very

userspace hypercall implementation

unmodified file system driver ad-hoc shims VFS emustub rump kernel

UKFS application (e.g. fs-utils)

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Step 3: a lot (2008 - 2011)

userspace hypercall interface

rump kernel

hypercall implementation

TCP/IP file systems device drvs syscalls

...

glue code

syscalls, vfs, etc. hijack application / service

  • support for all driver

subsystems

  • isolation from the host
  • stable hypercall interface
  • anykernel completed
  • production quality
  • rump kernels used for

testing NetBSD

  • no libc for rump kernels,

applications ran partially

  • n the host
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Step 3.5: visions (not an actual step)

  • ca. turn of the year 2011/2012:

“An anykernel architecture can be seen as a gateway from current all-purpose operating systems to more specialized operating systems running on ASICs. The anykernel enables the device manufacturer to provide a compact hypervisor and select only the critical drivers from the original OS for their purposes. The unique advantage is that drivers which have been used and proven in general purpose systems, e.g. the TCP/IP stack, may be included without modification as standalone drivers in embedded products.”

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Step 4: portability to POSIX 2007-2012, 2012-

buildrump.sh (2012-)

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4.4STEP: beyond POSIX (201[234])

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Step 5.1: rumprun (2013, 2014)

platform hypercall interface

rump kernel

hypercall implementation

TCP/IP file systems device drvs syscalls

...

glue code

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Step 5.2: rumprun (2013, 2014)

platform hypercall interface

rump kernel

hypercall implementation libc

syscall traps rump kernel calls

application(s) userspace libraries

TCP/IP file systems device drvs syscalls

...

glue code

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FINAL HALF

conclusions & other tidbits

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All le gory technical details: http://book.rumpkernel.org/

2nd edition is work in progress Will be available as free pdf, hopefully printed too

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Community

  • http://rumpkernel.org/
  • http://repo.rumpkernel.org/

– BSD-licensed source code

  • http://wiki.rumpkernel.org/
  • rumpkernel-users@lists.sourceforge.net
  • #rumpkernel on irc.freenode.net
  • @rumpkernel
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The actual conclusions

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You can make an omelette without breaking the kitchen!