Re: [PATCH v3 15/19] RISC-V: Linux Syscall Interface

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

On 27/12/2017 04:05, Palmer Dabbelt wrote:
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/riscv/arch-fork.h
> @@ -0,0 +1,27 @@
> +/* Internal definitions for thread-friendly fork implementation.  Linux/i386.
> +   Copyright (C) 2002-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sched.h>
> +#include <sysdep.h>
> +#include <tls.h>
> +
> +#define ARCH_FORK() \
> +  INLINE_SYSCALL (clone, 5,						      \
> +		  CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD, 0,     \
> +		  NULL, NULL, &THREAD_SELF->tid)

Why did you choose CONFIG_CLONE_BACKWARDS for riscv? My understanding
reading kernel/fork.c is default for newer ports should be the one 
without any BACKWARDS* define, x86_64 for instance (and arch/Kconfig:824 
seems to put CLONE_BACKWARDS on the 'ABI hall of shame' as well).