On 11:48 Fri 12 Mar 2021, Masahiro Yamada wrote:
Hi.
I think I am missing something, but
is there any particular reason to
use a different bit size between
a syscall and its userspace wrapper?
For example, for the unshare syscall,
unshare(2) says the parameter is int.
SYNOPSIS
#define _GNU_SOURCE
#include <sched.h>
int unshare(int flags);
In the kernel, it is unsigned long.
SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
{
return ksys_unshare(unshare_flags);
}
I guess the upper 32-bit will be
zeroed out in the c library when
sizeof(int) != sizeof(unsigned long)
(i.e. 64-bit system), but I'd like to know
why we do it this way.
Small nit! never mind ...but eye catching, Masahiro :) ...are you typing this on narrowed device, which allow only this much line length?? It's bloody narrow...don't you think so? Sorry, for the deviation. ~Bhaskar
-- Best Regards Masahiro Yamada
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