From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54409) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WwqUf-0007XR-In for qemu-devel@nongnu.org; Tue, 17 Jun 2014 06:20:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WwqUY-0001Ox-8w for qemu-devel@nongnu.org; Tue, 17 Jun 2014 06:19:57 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:34390) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WwqUT-0001Na-Uk for qemu-devel@nongnu.org; Tue, 17 Jun 2014 06:19:50 -0400 Received: from /spool/local by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 17 Jun 2014 20:19:40 +1000 From: Nikunj A Dadhania In-Reply-To: <53A01220.90009@suse.de> References: <1402574971-26672-2-git-send-email-nikunj@linux.vnet.ibm.com> <53A006A9.90108@suse.de> <871tunc288.fsf@linux.vnet.ibm.com> <53A01006.6080800@suse.de> <87y4wvamb3.fsf@linux.vnet.ibm.com> <53A01220.90009@suse.de> Date: Tue, 17 Jun 2014 15:49:26 +0530 Message-ID: <87vbrzale9.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v2] ppc: spapr-rtas - implement os-term rtas call List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf , qemu-devel@nongnu.org Cc: aik@au1.ibm.com, qemu-ppc@nongnu.org Alexander Graf writes: > On 17.06.14 11:59, Nikunj A Dadhania wrote: >> Alexander Graf writes: >>> On 17.06.14 11:30, Nikunj A Dadhania wrote: >>>> Alexander Graf writes: >>>>>> + spapr_rtas_register("ibm,os-term", rtas_ibm_os_term); >>>>>> + spapr_rtas_register("ibm,extended-os-term", rtas_ibm_ext_os_term); >>>>> Why do we need the extended-os-term if we don't do anything with it? >>>> Linux kernel checks for both of them because of legacy: >>>> >>>> arch/powerpc/kernel/rtas.c: >>>> >>>> void rtas_os_term(char *str) >>>> { >>>> [...] >>>> /* >>>> * Firmware with the ibm,extended-os-term property is guaranteed >>>> * to always return from an ibm,os-term call. Earlier versions without >>>> * this property may terminate the partition which we want to avoid >>>> * since it interferes with panic_timeout. >>> But we do not return from the RTAS call, so we don't adhere to the >>> extended semantics? >> But you would return without calling os-term call if >> ibm,extended-os-term isnt registered. For that reason I h ave defined a >> stub. > > I appreciate the hacker mentality, but Linux explicitly checks on > ibm,extended-os-term to ensure that the hypervisor does not stop the VM > when it calls ibm,os-term. However, the implementation above does stop > the VM when the guest calls ibm,os-term. Seems to be added to do just that: commit e9bbc8cde0e3c33b42ddbe1b02108cb5c97275eb Author: Anton Blanchard Date: Thu Feb 18 12:11:51 2010 +0000 powerpc/pseries: Call ibm,os-term if the ibm,extended-os-term is present We have had issues in the past with ibm,os-term initiating shutdown of a partition. This is confusing to the user, especially if panic_timeout is non zero. The temporary fix was to avoid calling ibm,os-term if a panic_timeout was set and since we set it on every boot we basically never call ibm,os-term. An extended version of ibm,os-term has since been implemented which gives us the behaviour we want: "When the platform supports extended ibm,os-term behavior, the return to the RTAS will always occur unless there is a kernel assisted dump active as initiated by an ibm,configure-kernel-dump call." This patch checks for the ibm,extended-os-term property and calls ibm,os-term if it exists. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt > Why was that check put into place? Regards Nikunj