From mboxrd@z Thu Jan 1 00:00:00 1970 From: Santosh Shukla Subject: Re: [PATCH] eal: map io resources for non x86 architectures Date: Fri, 18 Dec 2015 18:25:16 +0530 Message-ID: References: <2241331.HNmyzf8foi@xps13> <2979402.yeVYlcCDUH@xps13> <20151218053053.GL29571@yliu-dev.sh.intel.com> <20151218082139.GC18863@yliu-dev.sh.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: dev@dpdk.org To: Yuanhan Liu Return-path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by dpdk.org (Postfix) with ESMTP id 26FB02EDA for ; Fri, 18 Dec 2015 13:55:17 +0100 (CET) Received: by mail-pa0-f44.google.com with SMTP id q3so40207805pav.3 for ; Fri, 18 Dec 2015 04:55:17 -0800 (PST) In-Reply-To: <20151218082139.GC18863@yliu-dev.sh.intel.com> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Fri, Dec 18, 2015 at 1:51 PM, Yuanhan Liu wrote: > On Fri, Dec 18, 2015 at 01:24:41PM +0530, Santosh Shukla wrote: >> >> I guess we have done enough evaluation / investigation that suggest - >> >> so to map iopci region to userspace in arch agnostic-way - >> >> >> >> # either we need to modify kernel >> >> - Make sure all the non-x86 arch to support mapping for >> >> iopci region (i.e. pci_mmap_page_range). I don;t think its a correct >> >> approach though. >> >> or >> >> - include /dev/ioport char-mem device file who could do >> >> more than byte operation, Note that this implementation does not exist >> >> in kernel. I could send an RFC to lkml. >> > >> > Maybe you could propose the two to lkml, to get some feedbacks from >> > those kernel/ARM gurus? Please cc me if you do so. >> > >> >> The latter one I already shared old lkml thread, Pl. revisit my v1 0/6 >> patch [1] and in that refer [2]. > > Oops, sorry, a bit busy, that I didn't look at it carefully. My bad, > anyway. > >> Josh has already proposed to lkml but for some reason thread didn't >> went far. I can restart that discussion giving dpdk use-case as an >> example/ requirement. > > I had a quick go through of the discussion. Both hpa and Arnd seem > to be fine with the ioctl interface on /dev/port. Have you tried > that? And if you want to restart it, ioctl might be a better option > than /dev/ioport, judging from the discussion. > I tried legacy patch and re-writing with ioctl-way; doing changes in dpdk port as well in kernel, had to test on quite other hw not only arm64 though! so it will take time for me, I am travelling tomorrow so bit delayed, We'll post patch to lkml and share dpdk-virtio feedback perhaps by Monday. >> >> And for the former one, I'll have to check with linux-arm why iopci >> region not mappable. By grepping kernel source all i could see two >> commit - latest one is 415ae101 and older one 1da177e. Both has >> nothing to explain why >> if (mmap_state == pci_mmap_io) >> return -EINVAL; >> >> Setting pci io region to -EINVAL, should have fundamental reason for >> sure. But we'll have to check, for that I could post as a query rather >> a patch to lkml. > > No idea, such check should have been there in the very beginning > for some reason. And here is a quote from Arnd: > > Only powerpc, microblaze, alpha, sparc and xtensa allow > users to mmap I/O space, even though a lot of others could. > >> >> Note that dpdk already has out-of-tree implementation for >> dom0/xen-case too, it creates special device file which maps pci >> resources. so keep one more igb_uio char device so to map iopci region >> wont hurt much though! > > Xen is not a good example here; I'm even not sure it still works > or not :) > > --yliu >> [1] http://permalink.gmane.org/gmane.comp.networking.dpdk.devel/29531 >> >> > --yliu >> >> >> >> OR keep device file in user space (current approach) >> >> Right now Virtio-for-arm patches are blocked on this, let me know if >> >> someone has better approach/thought in mind. >> >> >> >> Thanks. >> >> >> >> > Then we can try a pci_mmap solution or, as you suggest, an interface in >> >> > drivers/char/mem.c >> >> >