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SubjectRe: [PATCH -mm] kexec jump -v9
Date
On Thursday, 15 of May 2008, Huang, Ying wrote:
> On Wed, 2008-05-14 at 15:30 -0700, Eric W. Biederman wrote:
> [...]
> > >
> > > + if (image->preserve_context) {
> > > + KJUMP_MAGIC(control_page) = KJUMP_MAGIC_NUMBER;
> > > + if (kexec_jump_save_cpu(control_page)) {
> > > + image->start = KJUMP_ENTRY(control_page);
> > > + return;
> >
> > Tricky, and I expect unnecessary.
> > We should be able to just have relocate_new_kernel return?
>
> OK, I will check this. Maybe we can move CPU state saving code into
> relocate_new_kernel.
>
> [...]
> > > -static void kernel_kexec(void)
> > > +static int kernel_kexec(void)
> > > {
> > > + int ret = -ENOSYS;
> > > #ifdef CONFIG_KEXEC
> > > - struct kimage *image;
> > > - image = xchg(&kexec_image, NULL);
> > > - if (!image)
> > > - return;
> > > - kernel_restart_prepare(NULL);
> > > - printk(KERN_EMERG "Starting new kernel\n");
> > > - machine_shutdown();
> > > - machine_kexec(image);
> > > + if (xchg(&kexec_lock, 1))
> > > + return -EBUSY;
> > > + if (!kexec_image) {
> > > + ret = -EINVAL;
> > > + goto unlock;
> > > + }
> > > + if (!kexec_image->preserve_context) {
> > > + kernel_restart_prepare(NULL);
> > > + printk(KERN_EMERG "Starting new kernel\n");
> > > + machine_shutdown();
> > > + }
> > > + ret = kexec_jump(kexec_image);
> > > +unlock:
> > > + xchg(&kexec_lock, 0);
> > > #endif
> >
> > Ugh. No. Not sharing the shutdown methods with reboot and
> > the normal kexec path looks like a recipe for failure to me.
> >
> > This looks like where we really need to have the conversation.
> > What methods do we use to shutdown the system.
> >
> > My take on the situation is this. For proper handling we
> > need driver device_detach and device_reattach methods.
> >
> > With the following semantics. The device_detach methods
> > will disable DMA and place the hardware in a sane state
> > from which the device driver can reclaim and reinitialize it,
> > but the hardware will not be touched.
> >
> > device_reattach reattaches the driver to the hardware.
>
> Yes. Current device PM callback is not suitable for hibernation (kexec
> based or original). I think we can collaborate with Rafael J. Wysocki on
> the new device drivers hibernation callbacks.

Thanks, I'm also open for collaboration. There will be a lot of work to do
related to the new callbacks, so any contribution is certainly welcome.

Thanks,
Rafael


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