On 01/08/11 19:59, Somebody in the thread at some point said:
(1) I think we're agreed that silence (mode 0, ignore), the
current
default, is probably the worst possible value.
(2) It's going to be really, really hard to [i] identify and [ii]
convince upstreams to fix all alignment issues. Where alignment traps
may be data-triggered, it will be nearly impossible to have confidence
that all corner cases have been tested.
I also think that it's unnecessary to eliminate all alignment issues --
in many cases, kernel fixups may actually be cheaper to run than the
defensive code necessary to avoid them, and hardware fixups are even
cheaper. Furthermore, running on an armv7 or higher processor won't
trigger the alignment traps at all, so we won't even know that there are
issues (just as we don't know, nor care, in an x86 context).
Thus my recommendation that we warn and fix up the alignment, rather
than warn and produce wrong results. (If you really want to force
someone to deal with these issues, you'd want warn+signal, and I would
strongly oppose making that the default).
Sounds right. The user is going to google why his log is filling with
these warnings if he cares and the problem is bad, and this covers his
code as well as distro code (with the small window where the alignment
policy is still 0 from running init through actually setting the
alignment policy to fix+log if he doesn't know about the kernel parameter).
If he doesn't use Fedora initscripts, then he's at the mercy of the
kernel default alignment policy of "mangle data silently" but that's not
a Fedora problem.
-Andy