2004-08-09  Paul Eggert  <eggert@cs.ucla.edu>
	[BZ #315]
	* manual/memory.texi (Obstacks Data Alignment): The default
	alignment is not 4: it is enough to hold any type of data.
	Problem reported by Benno in
	<http://sources.redhat.com/ml/libc-alpha/2004-08/msg00055.html>.
This commit is contained in:
Roland McGrath 2006-02-22 06:58:11 +00:00
parent edb72ee4e5
commit 11883883a5
2 changed files with 13 additions and 2 deletions

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@ -3,6 +3,14 @@
* sysdeps/unix/sysv/linux/x86_64/sys/epoll.h: Update comment, remove
__THROW from epoll_wait, to match .../linux/sys/epoll.h file.
2004-08-09 Paul Eggert <eggert@cs.ucla.edu>
[BZ #315]
* manual/memory.texi (Obstacks Data Alignment): The default
alignment is not 4: it is enough to hold any type of data.
Problem reported by Benno in
<http://sources.redhat.com/ml/libc-alpha/2004-08/msg00055.html>.
2005-11-15 Robert Millan <robertmh@gnu.org>
[BZ #2161]

View File

@ -1968,7 +1968,8 @@ obstack_next_free (@var{obstack-ptr}) - obstack_base (@var{obstack-ptr})
Each obstack has an @dfn{alignment boundary}; each object allocated in
the obstack automatically starts on an address that is a multiple of the
specified boundary. By default, this boundary is 4 bytes.
specified boundary. By default, this boundary is aligned so that
the object can hold any type of data.
To access an obstack's alignment boundary, use the macro
@code{obstack_alignment_mask}, whose function prototype looks like
@ -1980,7 +1981,9 @@ this:
The value is a bit mask; a bit that is 1 indicates that the corresponding
bit in the address of an object should be 0. The mask value should be one
less than a power of 2; the effect is that all object addresses are
multiples of that power of 2. The default value of the mask is 3, so that
multiples of that power of 2. The default value of the mask is a value
that allows aligned objects to hold any type of data: for example, if
its value is 3, any type of data can be stored at locations whose
addresses are multiples of 4. A mask value of 0 means an object can start
on any multiple of 1 (that is, no alignment is required).