Pavel Machek wrote:
Hi!
This helps complete the encapsulation of updates to page tables (or pages
about to become page tables) into accessor functions rather than using
memcpy() to duplicate them. This is both generally good for consistency
and also necessary for running in a hypervisor which requires explicit
updates to page table entries.
Hmm, I'm not sure if this kind of hypervisor can reasonably work with swsusp;
swsusp is just copying memory, it does not know which part of memory are page tables.
Pavel
There are good and bad things about this. Everything with swap suspend
should be fine for the suspend portion of things; it is when resuming
back up that one must take care to call the hypervisor functions for
reloading control registers and updating page tables.
I'm not sure that Xen can cope with that scenario - it would have to go
into shadowed mode first, then after resume, go back from shadow mode
into direct page table mode. Otherwise, as you say, making swap suspend
aware of what pages are page tables would be quite difficult and
needlessly complicate the code.
Since most hypervisors will likely provide a suspend/resume mechanism
that is external to the guest, most of this is a moot point anyways.
But I wondered if you thought the pgd_clone() accessor would make this
cleaner or if it is just most confusing:
#ifdef CONFIG_SOFTWARE_SUSPEND
/*
* Swap suspend & friends need this for resume because things like the
intel-agp
* driver might have split up a kernel 4MB mapping.
*/
char __nosavedata swsusp_pg_dir[PAGE_SIZE]
__attribute__ ((aligned (PAGE_SIZE)));
static inline void save_pg_dir(void)
{
memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE); <--- could be
clone_pgd_range()
}
Zach
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
| |
 |