Comment 30 for bug 36185

(In reply to comment #26)

> I know that some distributions simply enable it by default, which might be
> acceptable for their audience, but not for Ubuntu.

Would it be acceptable to have two installation targets say "default" and
"failsafe". So, by default DMA would be switched on (both during and after the
install) but if that failed you could install using "failsafe" which would
disable DMA (not to mention APIC, LAPIC and any others that cause issues) during
and after install. If it were clearly documented I would say most users would
be happy enough with this. If extra stuff could be added to the default where
it sensed a known bad dvdrom/controller and dropped back that would be better
again so as to expose as few people as possible to any kind of failure.

> If anyone can find out about prior efforts in this area in other projects in
> order to provide us with a starting point, we could perhaps get started on
> implementing a solution as early as the developer summit in November.

One thing that seems fairly apparent is that if those distros get away with this
then relatively few installations fail despite DMA being enabled. Ubuntu
understandably doesn't want to lock that hardware out. It seems that few would
need the "failsafe" option but it's important that it's there.