From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 4555B5A38 for ; Tue, 22 Dec 2015 03:54:14 +0100 (CET) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga103.jf.intel.com with ESMTP; 21 Dec 2015 18:54:13 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,462,1444719600"; d="scan'208";a="876420980" Received: from yliu-dev.sh.intel.com (HELO yliu-dev) ([10.239.66.49]) by orsmga002.jf.intel.com with ESMTP; 21 Dec 2015 18:54:12 -0800 Date: Tue, 22 Dec 2015 10:55:23 +0800 From: Yuanhan Liu To: "Xie, Huawei" Message-ID: <20151222025523.GF18863@yliu-dev.sh.intel.com> References: <1449027793-30975-1-git-send-email-yuanhan.liu@linux.intel.com> <1450321921-27799-1-git-send-email-yuanhan.liu@linux.intel.com> <1450321921-27799-2-git-send-email-yuanhan.liu@linux.intel.com> <20151222022541.GD18863@yliu-dev.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Cc: "Michael S. Tsirkin" , "dev@dpdk.org" , Victor Kaplansky Subject: Re: [dpdk-dev] [PATCH v2 1/6] vhost: handle VHOST_USER_SET_LOG_BASE request X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 Dec 2015 02:54:14 -0000 On Tue, Dec 22, 2015 at 02:41:43AM +0000, Xie, Huawei wrote: > > > > -----Original Message----- > > From: Yuanhan Liu [mailto:yuanhan.liu@linux.intel.com] > > Sent: Tuesday, December 22, 2015 10:26 AM > > To: Xie, Huawei > > Cc: dev@dpdk.org; Michael S. Tsirkin; Victor Kaplansky; Iremonger, > > Bernard; Pavel Fedin; Peter Xu > > Subject: Re: [PATCH v2 1/6] vhost: handle VHOST_USER_SET_LOG_BASE > > request > > > > On Mon, Dec 21, 2015 at 03:32:53PM +0000, Xie, Huawei wrote: > > > > + > > > > + /* > > > > + * mmap from 0 to workaround a hugepage mmap bug: mmap will be > > > > + * failed when offset is not page size aligned. > > > > + */ > > > s /will be failed/will fail/ > > > mmap will fail when offset is not zero. > I mistake for 4KB page size. Didn't follow you. > Please check if huge page size align is enough. It should be. However, I don't think we need bother to do that: first of all, it happened on few specific old kernels. And, "off" here is kind of guaranteed to be 0. Last, even it's not, mmaping it from 0 will resolve that. > > > Also we only know this workaround is for hugetlbfs. Not sure of > > other > > > tmpfs, so mention hugetlbfs here. > > > > I have already mentioned "to workaround a __hugepage__ mmap bug"; it's > > not enough? > Yes. > > > > > > + addr = mmap(0, size + off, PROT_READ | PROT_WRITE, MAP_SHARED, fd, > > 0); > > > > + if (addr == MAP_FAILED) { > > > > + RTE_LOG(ERR, VHOST_CONFIG, "mmap log base failed!\n"); > > > > + return -1; > > > > + } > > > > + > > > > + /* TODO: unmap on stop */ > > > > + dev->log_base = (uint64_t)(uintptr_t)addr + off; > > > (uint64_t)(uintptr_t)RTE_PTR_ADD(addr, off)? > > > > No, addr is of (void *) type, we should cast it to uint64_t type first, > > before adding it with "off". > > > > --yliu > RTE_PTR_ADD is the DPDK interface for pointer arithmetic operation. log_base is with "uint64_t" type, RTE_PTR_ADD() returns (void*), so it won't work here. --yliu