Re: [kvm-devel] kvm warning
On 8/9/07, Avi Kivity [EMAIL PROTECTED] wrote: Andrew Morton wrote: On Thu, 09 Aug 2007 01:48:07 +0300 Avi Kivity [EMAIL PROTECTED] wrote: Ingo Molnar wrote: * Andrew Morton [EMAIL PROTECTED] wrote: ia64 allmodconfig says drivers/kvm/Kconfig:14:warning: 'select' used by config symbol 'KVM' refers to undefined symbol 'PREEMPT_NOTIFIERS' hm, why doesnt ia64 pick up kernel/Kconfig.preempt, like all the other arches? Due to that ia64 also misses out on voluntary preempt and on preempt-bkl. Even more hm, how does ia64 manage to enable kvm? It 'depends on X86' at this moment. beats me. CONFIG_KVM doesn't get set. But it seems that kconfig wants to do error-checking on that item anyway. I could do a 'select PREEMPT_NOTIFIERS if X86' but it seems silly. I'd call it a Kconfig bug. I remember this issue well [1] ... it's a Kconfig deficiency indeed. Basically kconfig options for generic stuff cannot use select for symbols that are defined only for specific archs (here ia64 synthetically created this situation by failing to source kernel/Kconfig.preempt in its arch/ia64/Kconfig). Leads to no real build problems, but causes these bogus warnings to be printed on other archs (that don't have that symbol visible to them). Possible solutions could be to (1) source kernel/Kconfig.preempt from arch/ia64/Kconfig, or (2) Use default y if KVM for PREEMPT_NOTIFIERS (but this would be kludgy, horrible and tasteless). I'm not sure if select PREEMPT_NOTIFIERS if X86 would cut it to get rid of the bogus warnings, though. Solution (1) above sounds preferable, unless there are mysterious reasons why ia64 wants to avoid Kconfig.preempt (adding Tony Luck to Cc:). Satyam [1] Last time this happened was with something called ATARI_KBD_CORE. I submitted a patch that unfortunately degenerated into a flamewar :-) The bogus warnings remained (causing more traffic) for a month or so, before an alternate solution got finally merged. - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] kvm warning
Solution (1) above sounds preferable, unless there are mysterious reasons why ia64 wants to avoid Kconfig.preempt (adding Tony Luck to Cc:). Send me a patch and unless it causes more problems than it solves, I'll put it in. -Tony - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
[kvm-devel] kvm warning
ia64 allmodconfig says drivers/kvm/Kconfig:14:warning: 'select' used by config symbol 'KVM' refers to undefined symbol 'PREEMPT_NOTIFIERS' Because of commit 8928fb48c7a7f9053a55f1d0023cbc533f2b3663 Author: Avi Kivity [EMAIL PROTECTED] Date: Wed Jul 11 18:17:21 2007 +0300 KVM: Use the scheduler preemption notifiers to make kvm preemptible Current kvm disables preemption while the new virtualization registers are in use. This of course is not very good for latency sensitive workloads (on use of virtualization is to offload user interface and other latency insensitive stuff to a container, so that it is easier to analyze the remaining workload). This patch re-enables preemption for kvm; preemption is now only disabled when switching the registers in and out, and during the switch to guest mode and back. Contains fixes from Shaohua Li [EMAIL PROTECTED]. Signed-off-by: Avi Kivity [EMAIL PROTECTED] --- a/drivers/kvm/Kconfig +++ b/drivers/kvm/Kconfig @@ -11,6 +11,7 @@ if VIRTUALIZATION config KVM tristate Kernel-based Virtual Machine (KVM) support depends on X86 EXPERIMENTAL + select PREEMPT_NOTIFIERS select ANON_INODES ---help--- Support hosting fully virtualized guest machines using hardware ... a) is kvm supported on ia64 at all?? b) `select' is evil. Just Don't Do It. c) `select' is especially evil when it's done on some kernel-internal secret symbol like PREEMPT_NOTIFIERS. d) I can't see anything else in the kernel which sets or clears PREEMPT_NOTIFIERS so I'm rather wonderring why the config option exists at all. e) sched developers may not like KVM reaching over and twiddling their knobs for them. It all needs more thought, I think... - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] kvm warning
* Andrew Morton [EMAIL PROTECTED] wrote: ia64 allmodconfig says drivers/kvm/Kconfig:14:warning: 'select' used by config symbol 'KVM' refers to undefined symbol 'PREEMPT_NOTIFIERS' hm, why doesnt ia64 pick up kernel/Kconfig.preempt, like all the other arches? Due to that ia64 also misses out on voluntary preempt and on preempt-bkl. Ingo - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] kvm warning
Ingo Molnar wrote: * Andrew Morton [EMAIL PROTECTED] wrote: ia64 allmodconfig says drivers/kvm/Kconfig:14:warning: 'select' used by config symbol 'KVM' refers to undefined symbol 'PREEMPT_NOTIFIERS' hm, why doesnt ia64 pick up kernel/Kconfig.preempt, like all the other arches? Due to that ia64 also misses out on voluntary preempt and on preempt-bkl. Even more hm, how does ia64 manage to enable kvm? It 'depends on X86' at this moment. - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] kvm warning
On Thu, 09 Aug 2007 01:48:07 +0300 Avi Kivity [EMAIL PROTECTED] wrote: Ingo Molnar wrote: * Andrew Morton [EMAIL PROTECTED] wrote: ia64 allmodconfig says drivers/kvm/Kconfig:14:warning: 'select' used by config symbol 'KVM' refers to undefined symbol 'PREEMPT_NOTIFIERS' hm, why doesnt ia64 pick up kernel/Kconfig.preempt, like all the other arches? Due to that ia64 also misses out on voluntary preempt and on preempt-bkl. Even more hm, how does ia64 manage to enable kvm? It 'depends on X86' at this moment. beats me. CONFIG_KVM doesn't get set. But it seems that kconfig wants to do error-checking on that item anyway. btw, testing of Kconfig can be done for any architecture without installation of a toolchain for that architecture. Set $ARCH and run mrproper then use menuconfig/oldconfig/allmodconfig/allconfig as usual. Judging by the number of Kconfig problem I see, this is a big secret ;) - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] kvm warning
Andrew Morton wrote: On Thu, 09 Aug 2007 01:48:07 +0300 Avi Kivity [EMAIL PROTECTED] wrote: Ingo Molnar wrote: * Andrew Morton [EMAIL PROTECTED] wrote: ia64 allmodconfig says drivers/kvm/Kconfig:14:warning: 'select' used by config symbol 'KVM' refers to undefined symbol 'PREEMPT_NOTIFIERS' hm, why doesnt ia64 pick up kernel/Kconfig.preempt, like all the other arches? Due to that ia64 also misses out on voluntary preempt and on preempt-bkl. Even more hm, how does ia64 manage to enable kvm? It 'depends on X86' at this moment. beats me. CONFIG_KVM doesn't get set. But it seems that kconfig wants to do error-checking on that item anyway. I could do a 'select PREEMPT_NOTIFIERS if X86' but it seems silly. I'd call it a Kconfig bug. - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
