[PATCH] make the default alignment trap behavior configurable for user space

Russell King - ARM Linux linux at arm.linux.org.uk
Fri Mar 5 16:01:36 EST 2010

On Fri, Mar 05, 2010 at 04:01:01PM +0100, Uwe Kleine-König wrote:
> I like that patch.  (And I'd choose SIGBUS.)
> Is it still considered?

Absolutely not.

Alignment faults _remain_ a reality.  I've recently built a new glibc -
and guess what, it _relies_ upon alignment faults - I'm up to 2321607
userspace alignment faults.

If you decide to make alignment faults create a SIGBUS, then you kill any
system booting using some glibc's and with gconv support.

The hard fact is: the correct setting of the alignment fault handler is
_entirely_ _specific_ to the userspace you are running.  There is no one
correct setting for it.

To this end, recent kernels now have a kernel command line option to
chose the correct alignment fault handling behaviour - which is the right
thing to do since a multi-platform kernel may require different options
for their different userspaces.

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