[PATCH v4 2/2] manual: add architecture specific note on clone and clone3 syscalls

[Florian Weimer]

* Yury Khrustalev:

> +@subsection Architecture specific notes on system calls
> +
> +Because @code{syscall} function does not know anything about what a particular
> +system call does or what are the ABI requirements for it, it is important to be
> +aware of any additional requirements that the target kernel might have for
> +certain system calls.
> +
> +On AArch64 systems with enabled SME extension, system calls with @var{sysno}
> +equal to @code{SYS_clone} or @code{SYS_clone3} must be preceded with a call
> +to the @code{__arm_za_disable()} function in order to disable ZA state of SME
> +(see @url{https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst}
> +for details) . When the @code{clone()} wrapper provided by @theglibc{} is used,
> +this would happen automatically.

As this is discussing clone, I think you really should mention that
using syscall for clones that are not fork-style (vfork-style, or
thread-style) is NOT supported in general.  Not mentioning this
important restriction implies support.

Thanks,
Florian