From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@amacapital.net>, Kui Zhang <kuizhang@gmail.com>
Cc: x86@kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Stefani Seibold <stefani@seibold.net>
Subject: Re: [PATCH 2/3] doc,vdso: Make vDSO examples more portable
Date: Thu, 12 Jun 2014 13:01:31 -0700 [thread overview]
Message-ID: <539A071B.2080101@zytor.com> (raw)
In-Reply-To: <87f62cc3db04047f9edbf7bacac059396d7112f1.1402598632.git.luto@amacapital.net>
On 06/12/2014 11:47 AM, Andy Lutomirski wrote:
>
> +#include <asm/bitsperlong.h>
> +
This isn't portable in any way. This is probably not the right way to
do this.
The portable way to do this would be something like:
#include <limits.h>
#if ULONG_MAX > 0xffffffffUL
# define ELF_BITS 64
#else
# define ELF_BITS 32
#endif
There is also the option of looking for either __LP64__ or __ILP32__
which isn't 100% portable but works with all newer versions of gcc:
#ifndef ELF_BITS
# ifdef __LP64__
# define ELF_BITS 64
# elif defined(__ILP32__)
# define ELF_BITS 32
# else
# error "Unknown size, please define ELF_BITS"
# endif
#endif
... or something like that.
-hpa
next prev parent reply other threads:[~2014-06-12 20:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-12 18:47 [PATCH 0/3] vDSO reference parser updates and Go workaround Andy Lutomirski
2014-06-12 18:47 ` [PATCH 1/3] doc,vdso: Rename vdso_test.c to vdso_standalone_test_x86.c Andy Lutomirski
2014-06-12 18:47 ` [PATCH 2/3] doc,vdso: Make vDSO examples more portable Andy Lutomirski
2014-06-12 20:01 ` H. Peter Anvin [this message]
2014-06-12 18:47 ` [PATCH 3/3] x86,vdso: Hack to keep 64-bit Go programs working Andy Lutomirski
2014-06-12 20:21 ` H. Peter Anvin
2014-06-13 1:09 ` Andy Lutomirski
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