From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Tiejun" Subject: Re: [RFC][v3][PATCH 1/6] xen:x86: record RMRR mappings Date: Mon, 18 Aug 2014 15:42:04 +0800 Message-ID: <53F1AE4C.5050002@intel.com> References: <1408091238-18364-1-git-send-email-tiejun.chen@intel.com> <1408091238-18364-2-git-send-email-tiejun.chen@intel.com> <53EDD539.90403@citrix.com> <53EE436502000078000BA911@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53EE436502000078000BA911@mail.emea.novell.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: Jan Beulich , Andrew Cooper , ian.campbell@citrix.com, ian.jackson@eu.citrix.com, stefano.stabellini@eu.citrix.com, kevin.tian@intel.com, yang.z.zhang@intel.com Cc: xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 2014/8/16 0:29, Jan Beulich wrote: >>>> On 15.08.14 at 11:39, wrote: >>> @@ -80,6 +81,18 @@ static int __init acpi_register_rmrr_unit(struct acpi_rmrr_unit *rmrr) >>> return 0; >>> } >>> >>> +/* Record RMRR mapping to ready expose VM. */ >>> +static int __init rmrr_maps_register(struct acpi_rmrr_unit *rmrr) >>> +{ >> >> You absolutely need some protection against calling this function more >> than 128 times, or you need to do dynamic allocation of the storage. > > This together with ... > >>> --- a/xen/include/asm-x86/e820.h >>> +++ b/xen/include/asm-x86/e820.h >>> @@ -23,6 +23,8 @@ struct e820map { >>> struct e820entry map[E820MAX]; >>> }; >>> >>> +typedef struct e820map rmrr_maps_t; >> >> This type is a single map of RMRR regions, not multiple maps. >> rmrr_map_t please. > > ... this once again stresses what I stated previously: Piggybacking > on the E820 handling here is just the wrong approach. There's > really no correlation with E820 other than us wanting to use the > gathered information for (among other things) adjusting the guest > E820 table. But that doesn't in any way require any re-use of > non-suitable data structures. Why are you saying this is not suitable? We need a structure to represent a RMRR entry including three fields, start, size and type, and especially, essentially RMRR entry belongs to e820 table as one entry. > > In fact I don't see the need for this first patch anyway, as RMRRs > are already being put on a linked list as they get found. I.e. the Yes, that list, acpi_rmrr_unit, can be exposed here. But before you copy to guest, don't you need to grab those fields from that list then convert them as a suitable structure (mostly this is still same as e820entry) to be copied into a buffer? Thanks Tiejun > patch here just clones existing information. > > Jan > >