Re: [PATCH] swsuspend and CONFIG_DISCONTIGMEM=y

William Lee Irwin III
2002-11-15T12:05:11Z

[code snippet snipped]

On Fri, Nov 15, 2002 at 01:02:33PM +0100, Pavel Machek wrote:
> This certainly does not work. We'd need to do some deep magic in
> suspend_asm.S to copy pages back. [Well, deep magic... Same
> kmap_atomic.] But suspend_asm.S has to guarantee not touching any
> memory so the change is not quite trivial.

I wasn't entirely expecting it to work out of the box. I was really
trying to get the VM structure traversal and access in line with
the general case, and then worry (later) about deeper issues like
that once they arise. kmap_atomic() etc. should be no-ops without
highmem, so otherwise it'd be safe (at least on the save path), aside
from perhaps suggesting that highmem should work when it wouldn't.
The restore path, OTOH...

I should take a look at suspend_asm.S to get an idea of what you're
talking about with respect to its expectations being violated by
the code snippet I posted.

At some point in the past, I wrote:
>> I don't know what to make of highmem on laptops etc., but the VM's
>> conventions should not be that hard to follow; also, there are uses for
>> the swsusp functionality on other kinds of machines (e.g. checkpointing).
>> Pure computationally-oriented systems such as would make use of this
>> are somewhat different from my primary userbase to support, but I think
>> it would be valuable to generalize swsusp in this way, and so provide
>> rudimentary support for such users in addition to some small measure of
>> cleanup (i.e. the cleanup adds functionality).
>> Pavel, what do you think?

On Fri, Nov 15, 2002 at 01:02:33PM +0100, Pavel Machek wrote:
> I definitely want to support swsusp for server boxes, but I'm not 100%
> sure how to do that easily.
> Pavel

I'm not entirely sure either. Mostly I suspect that the deep arch
issues will be the tough ones, but things like this I can handle. =)

Thanks,
Bill