RE: move hyperv CHANNELMSG_UNLOAD from crashed kernel to kdump kernel

[KY Srinivasan]

> -----Original Message-----
> From: Olaf Hering [mailto:olaf@xxxxxxxxx]
> Sent: Wednesday, December 7, 2016 7:47 AM
> To: KY Srinivasan <kys@xxxxxxxxxxxxx>; vkuznets@xxxxxxxxxx
> Cc: gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx
> Subject: RE: move hyperv CHANNELMSG_UNLOAD from crashed kernel to
> kdump kernel
> 
> Am 7. Dezember 2016 16:04:29 MEZ, schrieb KY Srinivasan
> <kys@xxxxxxxxxxxxx>:
> 
> >Yes; I had played with this approach a while ago. The issue is that the
> >host knows about a
> >bunch of in memory state that will be different in the kexec kernel.
> >For instance if we did all
> >the cleanup as part of the boot sequence, we will need access to all
> >the interrupt/messaging
> >infrastructure that was set up in the previous kernel.
> 
> 
> Where is that stored?  Perhaps it should be put into one place,  so that the
> new kernel can find and use it.

All the state required to handle interrupts is needed as well as the state needed
to issue unload. Look at vmbus_isr() for the needed interrupt handling state. The entire
code path from the isr routine will have to be executed. Is there a mechanism for stashing away state
that can be retrieved in the context of the execed kernel.

K. Y
> 
> Olaf