I make some very rough port of golang runtime to genode (mostly for nova),
https://github.com/tor-m6/genode.git
This work is a side result of one of research project made in Innopolis
University.
It allow compilation and execution of simple go applications/packages (probably
without unsupported os features).
I use only gccgo version of golang compiler. Things like "go build" in cross
mode not supported yet (while we make
some techology to produce makefiles from "go build" to compilei go code, not
attached yet).
Other limitations see below.
It build a set of libraries, in form of "libport" and "noux-pkg" each (because
we need to run configure which is not
supported in libport), as static ones.
Also it build a set of standard golang packages (namely fmt, os, syscall,
runtime/etc) as files for gccgo compilation.
Note: Go runtinme support around 9 systems as backend. I use netbsd as simplest
one for the base for new system - "inno".
To implement context switching I have to develop it from the scratch; for stack
port use alloc_secondary_stack() from Genode.
I suspect that I need to use a low-level context switching from kernel (native
thread switch), this is not implemented yet.
Configuration after build
=========================
Golang package (like fmt) is an object file (e.g. fmt.o) which appears in
build/x86_64/noux-pkg/libgo/ directory and
subdirectories. This path should be included during golang/gccgo compilation
(not only linking). Built libraries for Go
will be in ${LIB_CACHE_DIR}/libgo/libgobegin.a
${LIB_CACHE_DIR}/libgo/libgolibbegin.a ${LIB_CACHE_DIR}/libgo/libgo.a
Current limitations
===================
- RAM quota in .run file should be >= 1300M:
genode do not support MAP_ANON flag, so, we cant reserve memory (544Gb)
for arena, and, therefore, go to Windows-like model
with "small" immediate allocation; it force 2GB limitation in code and
make direct allocation of ~1.1Gb
- can run in VM with 1 CPU only:
in general it support checking of CPU number (by backporting patch from
current genode code) and trying to run
everything, but it hangs somewhere in the middle due to recursive
locking (error "deadlock ahead" in acquire() in mutex.cc)
May be this is small mistake - don't have time to find and fix
(in this place due to slot_jump() gdb do not give
normal info related to stack). I found that problem during
stack unwind in ... runtime.startm -> runtime.newm ->
runtime.newm -> runtime.mcommoninit -> runtime.callers ->
runtime_callers() -> backtrace_full() ...
here it try to call -> strlcpy() -> _jmp_slot() and make again
guard inside this function
- it works only on x86_64, tested on nova kernel
genode do not support makecontex/setcontext/gencontext family; but it
is crucial to support go because of goroutine model;
I have to implement it by myself. It is machine-dependent; moreover,
context swiching do not work after direct port from
libc/etc - I have to make 1 step stack unwind procedure to jump using
stack frame to the next function. So, I add
everywhere compilation option -fno-omit-frame-pointer to be sure that
this approach works. Probably it need only for
implementation of the file mycontext.cc
- it can work on seL4 as well, while I did not submit additional dirty
changes for go runtime (I swithed to nova/gdb)
- any go application need to add 3 files into it
(may be it worth to place them in another library or libgo.a) -
dummy.cc with Genode initialization and some empty
functions which are not supported on genode, mycontext.cc and
myacontext.s with implementation of x86 [sg]etcontext
- during port I make a set of dirty fixes for absent on the platform
(genode/nova), in particular "empty" C implementaion of
sendfile(), getpgid(), lchown(), mount(), settimeofday(), mlock(),
munlock(), mlockall(), munlockall(), sigaltstack();
in go part of runtime port I also "damage" some functions, in
particualr route.sysctl(), broke poll.ReadDirent(), partially
broke logic in runtime.sysMap/sysReserve because of unsupported mem
range reservation, do not use ptrace, broke routing in
netbsd version of syscall.toRoutingMessage and some others, see patches
for libgo in repos/libports/src/lib/libgo/.
so, anything in Golang which use them will fail. Potentially new genode
releases will contain something which can replace
or fix these and other patched functions
- once I compile all code with -O3 option, and it hangs. I did not check
why...
Questions? [email protected], origin in https://github.com/tor-m6/genode.git
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