[PATCH][MTD] mtdpart.c: allow other drivers to get physical address of partition
joern at logfs.org
Fri Aug 3 19:02:48 EDT 2007
On Fri, 3 August 2007 12:45:45 -0700, Jared Hulbert wrote:
> > > Perhaps we want to set it up so that _if_ there is a process which can
> > > continue, it'll do so. Only when there's nothing runnable in userspace
> > > do we suspend an erase? In that case, perhaps we'd want some kind of
> > > hook in the idle loop?
> > Or we could just always suspend the erase and resume it the next time we
> > enter the kernel, either via system call or interrupt. Should allow the
> > process to make some progress without starving the erase. Would need
> > hooks as well, just in different places.
> Hmmm, we'd definitely benefit from having a hook in idle to trigger
> the erase to resume. Having hooks for entry into kernel space sounds
> interesting, but if you leave it too quickly and suspend the erase you
> don't make forward progress. However, I'm not sure how you'd
> determine whether a given process can continue without suspending the
Does the system ever idle in a userspace process? If not then you'd
have to come by one of my hooks before going into idle.
Even better, if the process does a system call, or an interrupt happens,
it will not access the XIP pages while the syscall/interrupt is
processed. So the erase may as well resume for the time being. And
potentially it can even run a little longer if no XIP faults happen.
The big question is how such a scheme would perform. It may turn out so
bad that we should rather copy the data, hand out RAM and wait for
memory pressure to remove those pages again.
I don't understand it. Nobody does.
-- Richard P. Feynman
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