RUMP KERNELS and {why,how} we got here

Transcription

1 RUMP KERNELS and {why,how} we got here New Directions in Operating Systems November 2014, London Antti Kantee, Fixup Software

2 Motivations want to run an application, not an OS want a better operating system operating system gets in the way

3 FIRST HALF what is an operating system

4 Summary of OS's s for enabling applications to run n*10 6 LoC optional goop defining relation between s and applications for protection, resource sharing, LoC

5 application application kernel

6 application application Server ( OS ) kernel

7 application application server server server kernel

8 application application application cpu core cpu core cpu core

9 application kernel

10 application application kernel

11 SECOND HALF what is a rump kernel

12 callers (i.e. clients ) rump kernel file systems TCP/IP device drvs syscalls... hypercall interface hypercall implementation platform

13 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 of a large number of its members

14 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 of a large number of its subsystems

15 A rump kernel does not provide threads, a scheduler, exec, or virtual memory, nor does it require privileged mode (or emulation of it) or interrupts > runs anywhere > integrates into other systems

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

17 same thread throughout entire stack AN EXAMPLE! application(s) userspace libraries libc unmodified POSIX userspace code (10 n lines) rump kernel calls rump kernel file systems TCP/IP syscall traps device drvs syscalls... unmodified NetBSD code (~10 6 lines) glue code Platform-independent glue code (~10 4 lines) hypercall interface hypercall implementation platform platform-specific code (~10 3 lines) e.g. Genode OS, Xen, userspace, bare-metal,

18 THIRD HALF (with operating systems, expect the unexpected) how rump kernels happened

19 Step 1: RUMP (2007) application userspace fs framework (userspace part) rump kernel VFS emustub unmodified file system ad-hoc shims hypercall implementation NetBSD userspace userspace syscalls, VFS, etc. userspace fs framework (kernel part) file system kernel

20 Step 2: UKFS (2007) application (e.g. fs-utils) UKFS rump kernel VFS emustub Q: how hard can implementing a few syscalls be? A: very unmodified file system ad-hoc shims hypercall implementation userspace userspace kernel

21 Step 3: a lot ( ) support for all 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 on the host application / service rump kernel file systems TCP/IP glue code hijack syscalls, vfs, etc. device drvs syscalls hypercall interface... hypercall implementation userspace

22 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 s from the original OS for their purposes. The unique advantage is that s which have been used and proven in general purpose systems, e.g. the TCP/IP stack, may be included without modification as standalone s in embedded products.

23 Step 4: portability to POSIX , buildrump.sh (2012-)

24 4.4STEP: beyond POSIX (201[234])

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28 Step 5.1: rumprun (2013, 2014) rump kernel file systems TCP/IP device drvs syscalls... glue code hypercall interface hypercall implementation platform

29 application(s) userspace libraries libc Step 5.2: rumprun (2013, 2014) rump kernel calls rump kernel file systems TCP/IP syscall traps device drvs syscalls... glue code hypercall interface hypercall implementation platform

30 FINAL HALF conclusions & other tidbits

31 All le gory technical details: 2 nd edition is work in progress Will be available as free pdf, hopefully printed too

32 Community BSD-licensed source code #rumpkernel on

33 The actual conclusions

34 You can make an omelette without breaking the kitchen!