Messages in this thread | | | Date | Sun, 27 Jan 2008 21:33:19 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] linux/types.h: always export 64bit aligned defines |
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On Sat, 26 Jan 2008 04:23:21 -0500 Mike Frysinger <vapier@gentoo.org> wrote:
> Some kernel headers exported to userspace rely on these 64bit aligned defines. > However, they are hidden behind __KERNEL_STRICT_NAMES at the moment which > means most of the time, they're never actually available. These these defines > dont actually conflict with normal userspace / C library types, there's no > reason to hide them behind the __KERNEL_STRICT_NAMES define. >
Maybe we shouldn't be using these helper macros in exported-to-userspace headers. Do you know which headers are affected? Did you consider jsut expanding the macros in situ for thse cases?
> --- > include/linux/types.h | 10 +++++----- > 1 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/include/linux/types.h b/include/linux/types.h > index f4f8d19..b80a263 100644 > --- a/include/linux/types.h > +++ b/include/linux/types.h > @@ -125,11 +125,6 @@ typedef __u64 u_int64_t; > typedef __s64 int64_t; > #endif > > -/* this is a special 64bit data type that is 8-byte aligned */ > -#define aligned_u64 unsigned long long __attribute__((aligned(8))) > -#define aligned_be64 __be64 __attribute__((aligned(8))) > -#define aligned_le64 __le64 __attribute__((aligned(8))) > - > /** > * The type used for indexing onto a disc or disc partition. > * > @@ -161,6 +156,11 @@ typedef unsigned long blkcnt_t; > > #endif /* __KERNEL_STRICT_NAMES */ > > +/* this is a special 64bit data type that is 8-byte aligned */ > +#define aligned_u64 unsigned long long __attribute__((aligned(8))) > +#define aligned_be64 __be64 __attribute__((aligned(8))) > +#define aligned_le64 __le64 __attribute__((aligned(8))) > + > /* > * Below are truly Linux-specific types that should never collide with > * any application/library that wants linux/types.h.
Seems relatively harmless.
But I'd have thought that if we're going to do this, we should create a standard naming convention for types which the kernel exports to userspace. Say, kern_*.
In which case the change becomes:
#define kern_aligned_u64 unsigned long long __attribute__((aligned(8))) #define kern_aligned_be64 __be64 __attribute__((aligned(8))) #define kern_aligned_le64 __le64 __attribute__((aligned(8)))
(exported to userspace)
and, inside __KERNEL__:
#define aligned_u64 kern_aligned_u64
etc. And, of course, all those bit of kernel headers which are presently using aligned_u64 in exposed-to-userspace places should be switched to kern_aligned_u4.
What thinkest thou?
If _that_ is all sane then we should do it all in a singe header file, say kern_types_for_userspace.h. include/linux/types.h would then do:
#include <linux/kern_types_for_userspace.h>
#ifdef __KERNEL__ #define aligned_u64 kern_aligned_u64 etc...
(all approximate, you-get-what-I-mean)
Duno if it'd be worth the effort, but it is The Right Thing To Do.
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