Hi folks, I've implemented a functional test for the cpu_set feature some time ago. I was going through the patch queue and realized the patch needed some respin, so I did it. I decided to try and see what is the state of the feature, considering last time I tried it was not working (segfaulting). Now, with the latest qemu-kvm things are on a much better shape, cpu_set is not giving me segfaults, and qemu monitor reports the new cpus added. 10:21:20 INFO | Adding 1 CPUs to guest 10:21:20 DEBUG| Sending monitor command: cpu_set 0 online 10:21:20 DEBUG| Sending monitor command: cpu_set 1 online 10:21:20 DEBUG| Sending monitor command: info cpus 10:21:20 DEBUG| Output of info cpus: * CPU #0: pc=0xffffffff8102e23d thread_id=11035 CPU #1: pc=0x0000000000000000 thread_id=11065 The address of the CPU #1 seems a little strange. The guest OS is completely unaware of any changes to the number of CPUs though. After doing some reading it seems to me that the reason why that is not happening is because SeaBIOS still doesn't have code to support CPU hot plugging as BochsBIOS did. I also looked after some documentation about how that feature is supposed to work, and didn't find it. So, assuming my understanding about the current status is correct: 1) Is anybody planning on adding the necessary support to SeaBIOS anytime soon? 2) How the whole functionality is supposed to work? My mental model goes like this: * cpu_set [total number of CPUs you want the system to have] online * Guest should notice new CPUS added to the system and they appear under /sys/devices/system/cpu/cpu*, initially offlined * The online status of each CPU is in /sys/devices/system/cpu/cpu*/online, and onlining it is just a matter of writing 1 to this file * It is not possible to downgrade the number of CPUs of the system during the lifetime of the VM process Thanks for your attention, Lucas -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
