From: "David S. Miller" <davem@redhat.com>
To: Sridhar Samudrala <sri@us.ibm.com>
Cc: acme@conectiva.com.br, netdev@oss.sgi.com,
lksctp-developers@lists.sourceforge.net
Subject: Re: net/sctp/sm_make_chunk.c alignment problems on parisc64
Date: Thu, 18 Sep 2003 19:55:25 -0700 [thread overview]
Message-ID: <20030918195525.28c17cb1.davem@redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0309171559540.3831-100000@localhost.localdomain>
On Wed, 17 Sep 2003 16:06:18 -0700 (PDT)
Sridhar Samudrala <sri@us.ibm.com> wrote:
> I don't see this problem on i386, ia64 or ppc64. Can someone
> familiar with parisc64 provide more details or submit a a patch to
> fix this problem?
As an example, if you have an structure member of type "char":
struct foo {
char a;
char b[4];
};
And then try to do something like this:
struct foo *p;
unsigned int *v;
v = (unsigned int *) (&p->b[0]);
*v = 0;
The build is going to explode on parisc because this simply is not
allowed. You cannot access a structure member as an object which
has larger alignment than is guarenteed for the type that member
has.
In the above example we're trying to access with 'unsigned int'
alignment a member which is only guarenteed to have the alignment
for a 'char'.
next prev parent reply other threads:[~2003-09-19 2:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-12 16:46 net/sctp/sm_make_chunk.c alignment problems on parisc64 Arnaldo Carvalho de Melo
2003-09-17 23:06 ` Sridhar Samudrala
2003-09-19 2:55 ` David S. Miller [this message]
2003-09-19 22:15 ` Sridhar Samudrala
2003-09-20 6:39 ` David S. Miller
2003-09-20 15:54 ` Arnaldo Carvalho de Melo
2003-09-22 22:06 ` Sridhar Samudrala
2003-09-25 20:52 ` Arnaldo Carvalho de Melo
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