Messages in this thread | | | Date | Fri, 7 Dec 2007 21:28:55 +0800 | From | "huang ying" <> | Subject | Re: [PATCH 3/4 -mm] kexec based hibernation -v7 : kexec hibernate/resume |
| |
On Dec 7, 2007 8:52 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote: > On Friday, 7 of December 2007, Huang, Ying wrote: > > This patch implements kexec based hibernate/resume. This is based on > > the facility provided by kexec_jump. The states save/restore code of > > ordinary kexec_jump is overridden by hibernate/resume specific > > code. > > Can you explain in more details how this works?
Two blocking notifier chain named kjump_chain_pre and kjump_chain_post are defined, the basic procedure of kexec jump is as follow:
call functions in kjump_chain_pre jump to peer kernel call functions in kjump_chain_post
A command is the first parameter of functions in chain. If A command is processed in a function, the function will execute and stop the chain (return NOTIFY_STOP), otherwise it will do nothing (return NOTIFY_DONE). If no function has interest in the command, the default behavior will be executed (kexec_vcall_pre, kexec_vcall_post).
So for each command the procedure is as follow:
KJUMP_CMD_HIBERNATE_WRITE_IMAGE: [chain] kexec_snapshot jump to kexeced kernel [chain] kexec_prepare_write_image /* in kexeced kernel */
KJUMP_HIBERNATE_RESUME: [chain] kexec_prepare_resume /* in kexeced kernel */ jump to kexec kernel [chain] kexec_resume
> > The ACPI methods are called at specified environment to conform > > the ACPI specification. A new reboot command is added to go to ACPI S4 > > state from user space. > > Well, I still don't like the amount of duplicated code introduced by this patch.
Yes, there are too many duplicated code. They should be merged. But I want to delay the merging until the kexec based hibernation code goes more stable.
> Also, IMO it should be using the mutual exclusion mechanisms used by the > existing hibernation code, ie. pm_mutex and the snapshot_device_available > atomic variable.
Now the kexec_lock is used as a mutex between kexec related operations. It seems reasonable to use pm_mutex and maybe snapshot_device_available to eliminate potential conflict between kexec based hibernation and u/swsusp.
Best Regards, Huang Ying
| |