Re: struct statfs/statfs64 in linux-generic

[Chung-Lin Tang <cltang@codesourcery.com>]

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On 13/11/15 2:28 AM, Chris Metcalf wrote:
> On 11/13/2013 11:34 PM, Chung-Lin Tang wrote:
>> On 13/11/13 8:58 PM, Joseph S. Myers wrote:
>>> On Wed, 13 Nov 2013, Chung-Lin Tang wrote:
>>>
>>>> 	(struct statfs): Use __alignof__(__u64) in alignment attribute
>>>> 	instead of 8.
>>>> 	(struct statfs64): Likewise.
>>> I don't like the use of __u64 here - that's a kernel type, not a glibc 
>>> one, and glibc headers shouldn't be using it.
>>>
>> Sure, how about __U64_TYPE? This seems in line with using __SWORD_TYPE
>> from <bits/types.h>
> 
> Looking at this, I wonder if we need the alignment attribute on the structure at all.  Given that the __field64 macro fields have that alignment attribute, the structure as a whole should also automatically have it, so it seems superfluous.  Does it work on nios2 if you remove the struct alignment directive?
> 
> The kernel version of the structure doesn't have any forced alignment on it.
> 

Yes, that works for nios2. Appears that struct stat/stat64 in
bits/stat.h doesn't have the struct alignment attributes either.
Updated patch attached.

Chung-Lin

2013-11-13  Chung-Lin Tang  <cltang@codesourcery.com>

	ports/
	* sysdeps/unix/sysv/linux/generic/bits/stat.h (__field64): Use
	__alignof__(type64) in alignment attribute instead of 8.
	* sysdeps/unix/sysv/linux/generic/bits/statfs.h (__field64): Use
	__alignof__(type64) in alignment attribute instead of 8.
	(struct statfs): Remove alignment attribute.
	(struct statfs64): Likewise.


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diff --git a/ports/sysdeps/unix/sysv/linux/generic/bits/stat.h b/ports/sysdeps/unix/sysv/linux/generic/bits/stat.h
index 6e74cec..feb5f2b 100644
--- a/ports/sysdeps/unix/sysv/linux/generic/bits/stat.h
+++ b/ports/sysdeps/unix/sysv/linux/generic/bits/stat.h
@@ -46,10 +46,10 @@
 # define __field64(type, type64, name) type name
 #elif __BYTE_ORDER == __LITTLE_ENDIAN
 # define __field64(type, type64, name) \
-  type name __attribute__((__aligned__(8))); int __##name##_pad
+  type name __attribute__((__aligned__ (__alignof__ (type64)))); int __##name##_pad
 #else
 # define __field64(type, type64, name) \
-  int __##name##_pad __attribute__((__aligned__(8))); type name
+  int __##name##_pad __attribute__((__aligned__ (__alignof__ (type64)))); type name
 #endif
 
 struct stat
diff --git a/ports/sysdeps/unix/sysv/linux/generic/bits/statfs.h b/ports/sysdeps/unix/sysv/linux/generic/bits/statfs.h
index 7063c7a..8aecb04 100644
--- a/ports/sysdeps/unix/sysv/linux/generic/bits/statfs.h
+++ b/ports/sysdeps/unix/sysv/linux/generic/bits/statfs.h
@@ -38,10 +38,10 @@
 # define __field64(type, type64, name) type name
 #elif __BYTE_ORDER == __LITTLE_ENDIAN
 # define __field64(type, type64, name) \
-  type name __attribute__((__aligned__(8))); int __##name##_pad
+  type name __attribute__((__aligned__ (__alignof__ (type64)))); int __##name##_pad
 #else
 # define __field64(type, type64, name) \
-  int __##name##_pad __attribute__((__aligned__(8))); type name
+  int __##name##_pad __attribute__((__aligned__ (__alignof__ (type64)))); type name
 #endif
 
 struct statfs
@@ -58,7 +58,7 @@ struct statfs
     __SWORD_TYPE f_frsize;
     __SWORD_TYPE f_flags;
     __SWORD_TYPE f_spare[4];
-  } __attribute__((__aligned__(8)));
+  };
 
 #undef __field64
 
@@ -77,7 +77,7 @@ struct statfs64
     __SWORD_TYPE f_frsize;
     __SWORD_TYPE f_flags;
     __SWORD_TYPE f_spare[4];
-  } __attribute__((__aligned__(8)));
+  };
 #endif
 
 /* Tell code we have these members.  */