Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752546AbbBRKAC (ORCPT ); Wed, 18 Feb 2015 05:00:02 -0500 Received: from mga01.intel.com ([192.55.52.88]:19812 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752286AbbBRJ76 convert rfc822-to-8bit (ORCPT ); Wed, 18 Feb 2015 04:59:58 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,600,1418112000"; d="scan'208";a="456165419" From: "Wang, Xiaoming" To: Jan Beulich CC: "chris@chris-wilson.co.uk" , "david.vrabel@citrix.com" , "lauraa@codeaurora.org" , "heiko.carstens@de.ibm.com" , "linux@horizon.com" , "Liu, Chuansheng" , "Zhang, Dongxing" , "takahiro.akashi@linaro.org" , "akpm@linux-foundation.org" , "linux-mips@linux-mips.org" , "ralf@linux-mips.org" , "xen-devel@lists.xenproject.org" , "boris.ostrovsky@oracle.com" , "konrad.wilk@oracle.com" , "d.kasatkin@samsung.com" , "pebolle@tiscali.nl" , "linux-kernel@vger.kernel.org" Subject: RE: [Xen-devel] [PATCH v4] modify the IO_TLB_SEGSIZE and IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW-IOMMU. Thread-Topic: [Xen-devel] [PATCH v4] modify the IO_TLB_SEGSIZE and IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW-IOMMU. Thread-Index: AQHQSn5MlHyw4zGUu0iv4XBiMSuM7Jz0GFgAgAFLKCCAAD2vAIAAh50w Date: Wed, 18 Feb 2015 09:56:53 +0000 Message-ID: References: <1424155903-4262-1-git-send-email-xiaoming.wang@intel.com> <54E321400200007800060865@mail.emea.novell.com> <54E46ACA0200007800060F5C@mail.emea.novell.com> In-Reply-To: <54E46ACA0200007800060F5C@mail.emea.novell.com> Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3669 Lines: 88 Dear Jan > -----Original Message----- > From: Jan Beulich [mailto:JBeulich@suse.com] > Sent: Wednesday, February 18, 2015 5:35 PM > To: Wang, Xiaoming > Cc: chris@chris-wilson.co.uk; david.vrabel@citrix.com; > lauraa@codeaurora.org; heiko.carstens@de.ibm.com; linux@horizon.com; > Liu, Chuansheng; Zhang, Dongxing; takahiro.akashi@linaro.org; > akpm@linux-foundation.org; linux-mips@linux-mips.org; ralf@linux- > mips.org; xen-devel@lists.xenproject.org; boris.ostrovsky@oracle.com; > konrad.wilk@oracle.com; d.kasatkin@samsung.com; pebolle@tiscali.nl; > linux-kernel@vger.kernel.org > Subject: RE: [Xen-devel] [PATCH v4] modify the IO_TLB_SEGSIZE and > IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW- > IOMMU. > > >>> On 18.02.15 at 10:09, wrote: > >> From: Jan Beulich [mailto:JBeulich@suse.com] > >> Sent: Tuesday, February 17, 2015 6:09 PM > >> >>> On 17.02.15 at 07:51, wrote: > >> > --- a/Documentation/kernel-parameters.txt > >> > +++ b/Documentation/kernel-parameters.txt > >> > @@ -3438,10 +3438,12 @@ bytes respectively. Such letter suffixes > >> > can also be entirely omitted. > >> > it if 0 is given (See > >> Documentation/cgroups/memory.txt) > >> > > >> > swiotlb= [ARM,IA-64,PPC,MIPS,X86] > >> > - Format: { | force } > >> > + Format: { | force | | } > >> > -- Number of I/O TLB slabs > >> > force -- force using of bounce buffers even if they > >> > wouldn't be automatically used by the kernel > >> > + -- Maximum allowable number of contiguous > >> slabs to map > >> > + -- The size of SW-MMU mapped. > >> > >> This makes no sense - the new numbers added aren't position > >> independent (nor were the previous and "force"). > >> > > Use "," can separate them one by one. > > We do it at lib/swiotlb.c > > Right, but the documentation above doesn't say so. > OK, I will add some comments on next patch version. > >> Also you are (supposedly) removing all uses of IO_TLB_DEFAULT_SIZE, > >> yet you don't seem to remove the definition itself. > >> > > I have change all uses of IO_TLB_DEFAULT_SIZE to io_tlb_default_size > > in lib/swiotlb.c > > Then are there any left elsewhere? If not, again - why don't you remove the > definition of IO_TLB_DEFAULT_SIZE? > There hasn't any IO_TLB_DEFAULT_SIZE left. I check the code IO_TLB_DEFAULT_SIZE only used in lib/swiotlb.c. And I have removed the definition of IO_TLB_DEFAULT_SIZE, in my patch @@ -120,15 +146,13 @@ unsigned long swiotlb_nr_tbl(void) } EXPORT_SYMBOL_GPL(swiotlb_nr_tbl); -/* default to 64MB */ -#define IO_TLB_DEFAULT_SIZE (64UL<<20) > >> Finally - are arbitrary numbers really okay for the newly added > >> command line options? I.e. shouldn't you add some checking of their > validity? > >> > > I have validity these code is OK. > > Example: > > BOARD_KERNEL_CMDLINE += swiotlb=, ,512,268435456 Io_tlb_segsize has > > been changed from 128 to 512 Io_tlb_default_size has been changed from > > 64M to 268435456 (256M) > > I specifically said "arbitrary numbers", which in particular includes zero and > non-power-of-2 values. If there are any restrictions on which numbers can > validly be passed here (and it very much looks like there are), such > restrictions should be enforced imo. > OK, we will validate for these variables' value in next patch version. > Jan Xiaoming -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/