From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH v3 15/24] xen/dts: Provide an helper to get a DT node from a path provided by a guest Date: Tue, 10 Mar 2015 13:58:00 +0000 Message-ID: <54FEF868.7090704@linaro.org> References: <1421159133-31526-1-git-send-email-julien.grall@linaro.org> <1421159133-31526-16-git-send-email-julien.grall@linaro.org> <1424705450.27930.164.camel@citrix.com> <54EB4EC7.4050502@linaro.org> <1424708838.27930.206.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YVKg3-0006GC-Qn for xen-devel@lists.xenproject.org; Tue, 10 Mar 2015 13:58:31 +0000 Received: by wibbs8 with SMTP id bs8so3209903wib.4 for ; Tue, 10 Mar 2015 06:58:28 -0700 (PDT) In-Reply-To: <1424708838.27930.206.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 Cc: xen-devel@lists.xenproject.org, tim@xen.org, stefano.stabellini@citrix.com List-Id: xen-devel@lists.xenproject.org On 23/02/15 16:27, Ian Campbell wrote: > On Mon, 2015-02-23 at 16:01 +0000, Julien Grall wrote: >> Hi Ian, >> >> On 23/02/15 15:30, Ian Campbell wrote: >>> On Tue, 2015-01-13 at 14:25 +0000, Julien Grall wrote: >>> >>>> +/* This limit is used by the hypercalls to restrict the size of the path */ >>>> +#define DEVICE_TREE_MAX_PATHLEN 1024 >>> >>> Is this something you've made up or derived from the DT spec/ePAPR etc? >> >> I didn't find a such requirements on the spec. > > I vaguely recall a limit on the length of a single node name, and a > limit on the depth which they may nest, which can be multiplied. It's > probably an unhelpfully large number though, so... > >> I chose this number based on the linux pathlen because the path is also >> used in the sysfs (/sys/firmware/devicetree). > > ...that's a good as anything I suppose! Hmmm... I'm not so sure about the 1024 limit anymore. Linux is defining PATH_MAX to 4096 but I don't see many usage in the sysfs code. And this value may change from one OS to another. Although, 1024 sounds a very long path to write in the configuration file... Maybe we should support alias too? Regards, -- Julien Grall