From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= Subject: Re: Commit dd6d87 breaks serial console Date: Wed, 23 Jul 2014 10:31:43 +0200 Message-ID: <53CF72EF.1040603@citrix.com> References: <53C40054.8080400@citrix.com> <53C40468.8030401@citrix.com> <53C418C0.805@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Zhang, Yang Z" , Andrew Cooper , xen-devel , Jan Beulich , "Tim (Xen.org)" , "Tian, Kevin" , Keir Fraser List-Id: xen-devel@lists.xenproject.org On 15/07/14 03:24, Zhang, Yang Z wrote: > Roger Pau Monn=E9 wrote on 2014-07-15: >> On 14/07/14 18:25, Andrew Cooper wrote: >>> On 14/07/14 17:07, Roger Pau Monn=E9 wrote: >>>> Hello, >>>> >>>> The following commit: >>>> >>>> commit dd6d87a4fcc8350c752e389abb3bcd8479c37555 >>>> Author: Jan Beulich >>>> Date: Fri Jun 20 10:26:37 2014 +0200 >>>> >>>> VT-d: drop redundant calls to invalidate_sync() >>>> = >>>> The call tree iommu_flush_iec_index() -> __iommu_flush_iec() alrea= dy >>>> invokes invalidate_sync(). Removing the superfluous instances at o= nce >>>> allows the function to become static. >>>> = >>>> Signed-off-by: Jan Beulich >>>> Reviewed-by: Andrew Cooper >>>> Acked-by: Yang Zhang >>>> Breaks serial console on my box, this is all the output I get with >>>> this commit applied: >>> >>> Are you sure you have bisected this correctly? >>> >>> Unless there is some hardware side-effect of issuing two qinvalidate >>> wait descriptors back-to-back, the change still looks to be good. >>> Alternately, are we missing a hardware erratum for your system? >> >> Just for the record, setting iommu=3Dno-intremap solves the problem, so >> I'm quite sure I've bisected it right. This is on a Xeon W3550, I can >> provide whatever other hardware information is needed. > = > It is so strange. The patch is really simple. Does Xen still alive when s= erial console breaks? Also, can you try to add invalidate_sync one by one t= o figure which one caused the problem? Yes, Xen seems to work fine (apart from the serial console), I can access Dom0 using ssh and create guests. The invalidate_sync that prevents this problem is the one in ioapic_rte_to_remap_entry, I have successfully removed the other invalidate_sync in msi_msg_to_remap_entry without problems. Roger.