From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH v6 09/31] xen/arm: ITS: Add APIs to add and assign device Date: Wed, 9 Sep 2015 17:19:26 +0100 Message-ID: <55F05C0E.9020908@citrix.com> References: <1441019208-2764-1-git-send-email-vijay.kilari@gmail.com> <1441019208-2764-10-git-send-email-vijay.kilari@gmail.com> <55E884BD.5080503@citrix.com> <1441805282.24450.324.camel@citrix.com> <55F037AD.6060606@citrix.com> <1441811273.24450.334.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1441811273.24450.334.camel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , vijay.kilari@gmail.com, stefano.stabellini@eu.citrix.com, stefano.stabellini@citrix.com, tim@xen.org, xen-devel@lists.xen.org Cc: Prasun.Kapoor@caviumnetworks.com, Vijaya Kumar K , manish.jaggi@caviumnetworks.com List-Id: xen-devel@lists.xenproject.org On 09/09/15 16:07, Ian Campbell wrote: >> In the ITS, discard means removing the mapping from the MSI (eventID) to >> the LPI. > > Table 6-6 in the gic arch spec (ARM IHI 0069A (ID060315)) says about the > discard ITS command "Translates the event defined by EventID and DeviceID > and instructs the appropriate Redistributor to remove the pending state of > the interrupt. It also ensures that any caching in the Redistributors > associated with a specific EventID is consistent with the configuration > held in memory." > > And section 6.3.4 seems to agree _except_ for the pseudo code which does > indeed seem to include setting the corresponding ITE entry to invalid. > > Given that the pseudocode for CLEAR appears to match how DISCARD is > decribed (infact the descrpitions of CLEAR and DISCARD look functionally > identical to me) I'm inclined to believe the pseudo code for DISCARD, i.e. > the docs are misleading and you are correct that DISCARD is more than just > clearing the pending state. > > The older PRD03-GENC-010745 24.0 looks to be more correct. > > So sorry for the noise, that'll teach me to believe docs. Actually, I didn't read the newer spec but remembered from what I read on the PRD03-* one. After reading the newer spec, the description doesn't match the pseudo-code. Might be worth to ask ARM about to clarify the behavior? Regards, -- Julien Grall