Re: Bug#609371: linux-image-2.6.37-trunk-sparc64: module scsi_mod:

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

* Steven Rostedt (rostedt@goodmis.org) wrote:
> On Wed, 2011-01-19 at 13:40 -0800, David Miller wrote:
> 
> > My concern is that if there is ever a u64 or similarly "long long"
> > typed member in these tracing structures, it will not be aligned
> > sufficiently to avoid unaligned access traps on 32-bit systems.
> 
> The structure that gets placed in this section is the ftrace_event_call.
> It consists only of pointers, a struct list_head, a couple of "int", and
> a struct trace_event, which consists of: a struct hlist_node, a struct
> list_head, an int, and a pointer.
> 
> None of these are more than "long" and I don't foresee them needing a
> long long type. I think assuming that a long is the largest item should
> due.
> 
> We can add a comment next to these structures specifying this
> dependency, and hopefully it would be updated if we ever do include a
> long long in them.

I still wonder how a 32-bit system can generate an unaligned access trap for an
access to a 64-bit variable aligned on 32-bit, given that there is, by
definition, no 64-bit memory accesses available on the architecture ?

Mathieu


-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com