> Yes, for regular function calls,
> but at least in the case of NetBSD,
> not for syscalls.
Those are the registers Linux uses for system calls on MIPS.
They are documented as such here:
https://www.man7.org/linux/man-pages/man2/syscall.2.html
> The second table shows the registers used
> to pa
> because the portable c api layer and syscall abi layer
> has a large enough gap that applications can break
> libc internals by doing raw syscalls.
I think that problem cannot really be fixed.
System call users just have to be aware of it.
It's true that using certain system calls can clobber l
> note: some syscalls / features don't work without asm
> (posix thread cancellation, vfork, signal return,..)
That's true. On the other hand, POSIX compliance
is not always a goal or a requirement.
> and using raw syscalls outside of the single runtime the
> application is using is problematic (
> I see systems making it more difficult for code to make syscalls,
> not easier.
That's true.
I think it's because other systems can afford to keep that ABI unstable.
Since Linux is an independently developed kernel, it _must_ be possible
to target the kernel directly with no user space compone
> Now the question comes is the argument long or some other type?
I believe so. Every library I've seen and the kernel itself uses long.
Other types just get typecasted to long. I think it's just supposed to
mean "register type" since all the arguments must be in registers.
> E.g. for some 32bit
> As noted by J. Wakely, you don't need to have one variant
> for each number of arguments.
Yes, he is right about that. I have already deleted
all the variants from my code since the variadic
builtin will be able to generate optimal code,
unlike a variadic C function.
> I assume you're talking a
> There is quite a bit of variance in how the kernel is entered.
I assume you mean the vDSO. It is also documented and stable.
https://www.kernel.org/doc/html/latest/admin-guide/abi-stable.html#vdso
> Unless otherwise noted, the set of symbols with any given version
> and the ABI of those symbol
> What's the advantage of the _1, _2 etc. forms?
Now that you mention it... I don't believe there are any.
> The compiler knows how many arguments you're passing,
> why can't there just be one built-in handling all cases?
You're right about that.
When I started working on this I just mirrored t
Hello! I'm a beginner when it comes to GCC development.
I want to learn how it works and start contributing.
Decided to start by implementing something relatively simple
but which would still be very useful for me: Linux builtins.
I sought help in the OFTC IRC channel and it was suggested
that I di
