How to rewrite the OS using C by strong type

How to rewrite the OS using C by strong type Metasepi Project / Kiwamu Okabe

Who am I? ☆ http://www.masterq.net/ ☆ Organizer of Metasepi Project ☆ A developer of Ajhc Haskell compiler ☆ A Debian Main...

Agenda ☆ [1] Problems of OS using C ☆ [2] Type safety ☆ [3] Existing OS using strong type ☆ [4] Snatch-driven development ...

[1] Problems of OS using C ☆ Most OS uses C language ☆ C is good for system programming ☆ But C occurs many problems

Buffer overrun ☆ Pointer to array doesn't know the length

Page fault in kernel ☆ Page fault in user space => SEGV ☆ Page fault in kernel space => Halt!

Weak type ☆ Great use of (void *) type ☆ NetBSD kernel uses 45130 times! $ pwd /home/kiwamu/src/netbsd/sys $ grep "void *"...

[2] Type safety ☆ Get less runtime errors

Avoid buffer overrun Strong type avoids buffer overrun.

Avoid page fault in kernel Only touch the area constructed.

Flexibility without weak type ☆ Algebraic data type data Node = Leaf Integer | Branch Node Node ☆ Type class class Functo...

Kernel needs strong type ☆ IoT:Internet of Things ☆ Poor hardware, and Rich feature ☆ Many custom requests shower kernel ☆...

[3] Existing OS using strong type Alreadly we have. ☆ Funk http://home.gna.org/funk/ ☆ snowflake-os https://code.google.c...

Poor design and less functions ☆ Design from scratch ☆ Polling interrupt ☆ Not have bus driver ☆ Support less devices ☆ On...

No compatible POSIX

[4] Snatch-driven development Rewrite kernel using C with strong type by little and little.

UNIX like OS needs reentrant

Strong type OS uses polling intr

Ajhc Haskell compiler Context can run without lock.

[5] Demo The proof of the pudding is in the eating.

MCU app without OS #1 https://github.com/ajhc/demo-cortex-m3

MCU app without OS #2 Memory map

MCU app with OS https://github.com/ajhc/demo-cortex-m3

[6] Case study of Snatch We found some idioms that are useful to rewrite C language with Haskell.

Idiom1: Call function C and Haskell call with each other.

Idiom2: Read/Write memory Haskell can read/write memory directly.

Idiom3: Read/Write struct Read structs chained with pointer.

Idiom4: Foreign Primitives Directly insert the text following const.

[7] Future work ☆ Benchmark ☆ Pointer combinator ☆ Share state between contexts ☆ Porting libraries running on GHC ☆ Debug...

Try to use the other language ☆ ATS http://www.ats-lang.org/ JATS-UG - Japan ATS User Group http://jats-ug.metasepi.org/ ☆...

Workshop at Nagoya ☆ Functional MCU programing workshop at Nagoya ☆ Meeting minutes http://metasepi.org/posts/2014-01-05-m...