Re: [9front] Go: "exec header invalid"

[ori@eigenstate.org]

Quoth sml <sml@firstpost.pub>:
> > Am 15.03.2022 um 12:15 schrieb Philip Silva <philip.silva@protonmail.com>:
> > 
> > Actually there's also a 500$ bounty for this
> > 
> > http://fqa.9front.org/appendixb.html
> 
> I would like to add 50$ for this.
> 
> 
> At the moment, I’m trying to understand how plan9/arm is implemented, to get an idea what needs to be done for plan9/arm64. 
> 
> As far as I understand,  /src/syscall/mksysnum_plan9.sh in go is used to get the information from /src/libc/9syscall/sys.h from plan9, using it in /src/syscall/zsysnum_plan9.go and at the beginning of /src/runtime/sys_plan9_arm.s.
> 
> /src/runtime/defs_plan9_arm.go is the information from /arm/include/ureg.h with getter and setter functions.

There's no direct translation for most of them.
> 
> But there are files like:
> 	src/runtime/os_plan9_arm.go

	This just looks like it papers over the
	fact that arm32 has no cycle counter;
	not sure if arm64 has it -- if it does,
	we should use it, if not, we should keep
	this hack.

> 	src/runtime/rt0_plan9_arm.s

	This code jumps into the runtime, after
	setting up the arguments in a way that
	rt0_go expects. Roughly the equivalent
	of /sys/src/libcarm64/main9.s, though
	the work is split differently, and go
	does a lot more.

> 	/ src/runtime/sys_plan9_arm.s (the part below the sysnums)

	this is the glue that the go runtime uses to
	talk to the OS; a thin abstraction layer over
	the system calls.

> 	/src/syscall/asm_plan9_arm.s

	A generic wrapper to do syscalls. Plan 9
	has a wrapper per syscall, generated in
	/sys/src/libc/9syscall/mkfile, go has
	a generic 'Syscall(num, args...)' func.

> 	/src/syscall/syscall_plan9.go

	The actual syscall package -- it's not arm
	specific, so you shouldn't need to touch it.

> 	/src/syscall/zsyscall_plan9_arm.go

	Looks like generated code, don't see why it'd
	need to be adjusted, since our types are the
	same across all archs.

> for which I cannot find the source in the plan9 code.
> 
> Is there documentation about the go code itself, regarding the machine dependent parts?

Read the code, read the comments, ask quesstions. Not aware of
any good docs.