Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly
On Fri, Apr 29, 2011 at 01:49:21PM +, KY Srinivasan wrote: 2) Windows host would not permit reloading the driver without rebooting the guest. That's a different issue, and one that I am very surprised to hear. That kind of invalidates ever being able to update the driver in a guest for a long-running system that you want to migrate and not reboot. That sounds like a major bug in hyper-v, don't you agree? In practical terms, I am not sure this is a major problem. If the root device Is managed by a Hyper-V driver, then you cannot unload that driver and drivers it depends on anyway. I don't run my hyper-v guests using the hyper-v driver for my root devices, so in my setup, it is possible to unload the whole vmbus subsystem and drivers and reload it without any system interruption. Now I have never tried that... :) Greg, I am open to either approach here: 1) I could drop this patch and restore the exit function. 2) I could keep the patch as is, but add additional comments to capture this discussion. Let me know what you prefer and I will send the remaining patch-set with the agreed upon changes. As you all are happy with not having this be unloaded, I'll go with 2) as it is your code to maintain and support, not mine. Just resend it with some more comments as I explained, and the rest, and I'll queue them up when I get caught up on my patch queue (I only have 381 to get through, the end is near!) thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
RE: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly
-Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Friday, April 29, 2011 11:11 AM To: KY Srinivasan Cc: Greg KH; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org; Haiyang Zhang; Abhishek Kane (Mindtree Consulting PVT LTD) Subject: Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly On Fri, Apr 29, 2011 at 01:49:21PM +, KY Srinivasan wrote: Just resend it with some more comments as I explained, and the rest, and I'll queue them up when I get caught up on my patch queue (I only have 381 to get through, the end is near!) Thanks Greg; soon after I sent you this patch-set, I had also sent a single patch to address a redundant assignment: 0001-Staging-hv-Do-not-re-set-the-bus-name.patch Please drop this patch. I will deal with this issue as part of the remaining patch-set I will be sending now. Regards, K. Y thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
RE: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly
-Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Friday, April 29, 2011 11:11 AM To: KY Srinivasan Cc: Greg KH; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org; Haiyang Zhang; Abhishek Kane (Mindtree Consulting PVT LTD) Subject: Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly Just resend it with some more comments as I explained, and the rest, and I'll queue them up when I get caught up on my patch queue (I only have 381 to get through, the end is near!) Done; I just resent the remaining patches with comments and corrections you had recommended. With regards to asking for a review, should I wait until all these patches are applied? Regards, K. Y ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly
On Fri, Apr 29, 2011 at 10:02:43PM +, KY Srinivasan wrote: -Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Friday, April 29, 2011 11:11 AM To: KY Srinivasan Cc: Greg KH; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org; Haiyang Zhang; Abhishek Kane (Mindtree Consulting PVT LTD) Subject: Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly Just resend it with some more comments as I explained, and the rest, and I'll queue them up when I get caught up on my patch queue (I only have 381 to get through, the end is near!) Done; I just resent the remaining patches with comments and corrections you had recommended. With regards to asking for a review, should I wait until all these patches are applied? Yes, unless you know of any other changes you want to make to the vmbus core. thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
RE: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly
-Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Friday, April 29, 2011 7:14 PM To: KY Srinivasan Cc: Greg KH; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org; Haiyang Zhang; Abhishek Kane (Mindtree Consulting PVT LTD) Subject: Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly On Fri, Apr 29, 2011 at 10:02:43PM +, KY Srinivasan wrote: -Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Friday, April 29, 2011 11:11 AM To: KY Srinivasan Cc: Greg KH; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org; Haiyang Zhang; Abhishek Kane (Mindtree Consulting PVT LTD) Subject: Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly Just resend it with some more comments as I explained, and the rest, and I'll queue them up when I get caught up on my patch queue (I only have 381 to get through, the end is near!) Done; I just resent the remaining patches with comments and corrections you had recommended. With regards to asking for a review, should I wait until all these patches are applied? Yes, unless you know of any other changes you want to make to the vmbus core. Thanks. Currently, I am not planning to make any changes to the vmbus core. Regards, K. Y ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly
On Wed, Apr 27, 2011 at 02:31:18AM +, KY Srinivasan wrote: -Original Message- From: Greg KH [mailto:g...@kroah.com] Sent: Tuesday, April 26, 2011 6:46 PM To: KY Srinivasan Cc: gre...@suse.de; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org; Haiyang Zhang; Abhishek Kane (Mindtree Consulting PVT LTD) Subject: Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly On Tue, Apr 26, 2011 at 09:20:25AM -0700, K. Y. Srinivasan wrote: The vmbus driver cannot be unloaded; the windows host does not permit this. Cleanup accordingly. Woah, you just prevented this driver from ever being able to be unloaded. It was never unloadable; while the driver defined an exit routine, there were couple of issues unloading the vmbus driver: 1) All guest resources given to the host could not be recovered. Is this a problem in the Linux side? If so, that could easily be fixed. 2) Windows host would not permit reloading the driver without rebooting the guest. That's a different issue, and one that I am very surprised to hear. That kind of invalidates ever being able to update the driver in a guest for a long-running system that you want to migrate and not reboot. That sounds like a major bug in hyper-v, don't you agree? All I did was acknowledge the current state and cleanup accordingly. This is not unique to Hyper-V; for what it is worth, the Xen platform_pci driver which is equivalent to the vmbus driver is also not unlodable (the last time I checked). Why isn't that allowed to be unloaded? What happens if it does? I would like to see the following be possible from Linux: - running Linux guest on hyperv - need to migrate to a newer version of hyper-v - pause long-running userspace processes. - unload hyperv modules - migrate guest to newer hyperv version (possible different host machine) - load newer hyperv modules - resume long-running guest processes If this isn't possible due to hyper-v bugs, then I guess we need to be able to live with it, but we had better advertise it pretty well as I know people will want to be able to do the above sequence for their guest instances. If so, can you expand this patch to say more in the changelog entry, and resend the remaining patches that I didn't apply as they are now gone from my pending-patch queue. That's not a cleanup that's a major change in how things work. I'm sure, if you want to continue down this line, there are more things you can remove from the code, right? What is the real issue here? What happens if you unload the bus? What goes wrong? Can it be fixed? This needs to be fixed on the host side. I have notified them of the issue. Ok, so if this is going to be fixed, why do we need to prevent this from ever being possible to have happen on our side? thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
Re: [PATCH 08/25] Staging: hv: vmbus_driver cannot be unloaded; cleanup accordingly
On Tue, Apr 26, 2011 at 09:20:25AM -0700, K. Y. Srinivasan wrote: The vmbus driver cannot be unloaded; the windows host does not permit this. Cleanup accordingly. Woah, you just prevented this driver from ever being able to be unloaded. That's not a cleanup that's a major change in how things work. I'm sure, if you want to continue down this line, there are more things you can remove from the code, right? What is the real issue here? What happens if you unload the bus? What goes wrong? Can it be fixed? This is a pretty big commitment... thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
