From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751023AbcFDLCm (ORCPT ); Sat, 4 Jun 2016 07:02:42 -0400 Received: from smtp.nue.novell.com ([195.135.221.5]:32971 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750809AbcFDLCk (ORCPT ); Sat, 4 Jun 2016 07:02:40 -0400 Date: Sat, 4 Jun 2016 19:01:56 +0800 From: joeyli To: Dan Williams Cc: "Lee, Chun-Yi" , Ross Zwisler , "Rafael J. Wysocki" , "linux-nvdimm@lists.01.org" , Linux ACPI , "linux-kernel@vger.kernel.org" , Gary Lin Subject: Re: [PATCH] libnvdimm, nfit: treat volatile virtual CD region as read-only pmem Message-ID: <20160604110156.GA4558@linux-rxt1.site> References: <1464938015-5489-1-git-send-email-jlee@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dan, Thanks for your review. On Fri, Jun 03, 2016 at 12:27:34PM -0700, Dan Williams wrote: > On Fri, Jun 3, 2016 at 12:13 AM, Lee, Chun-Yi wrote: > > This patch adds codes to treat a volatile virtual CD region as a > > read-only pmem region, then read-only /dev/pmem* device can be mounted > > with iso9660. > > > > It's useful to work with the httpboot in EFI firmware to pull a remote > > ISO file to the local memory region for booting and installation. > > > > Wiki page of UEFI HTTPBoot with OVMF: > > https://en.opensuse.org/UEFI_HTTPBoot_with_OVMF > > > > Signed-off-by: Lee, Chun-Yi > > Cc: Gary Lin > > Cc: Dan Williams > > Cc: Ross Zwisler > > Cc: "Rafael J. Wysocki" > > --- > > drivers/acpi/nfit.c | 8 +++++++- > > drivers/nvdimm/region_devs.c | 26 +++++++++++++++++++++++++- > > include/linux/libnvdimm.h | 2 ++ > > 3 files changed, 34 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c > > index 2215fc8..b100a17 100644 > > --- a/drivers/acpi/nfit.c > > +++ b/drivers/acpi/nfit.c > > @@ -1949,6 +1949,7 @@ static int acpi_nfit_init_mapping(struct acpi_nfit_desc *acpi_desc, > > switch (nfit_spa_type(spa)) { > > case NFIT_SPA_PM: > > case NFIT_SPA_VOLATILE: > > + case NFIT_SPA_VCD: > > nd_mapping->start = memdev->address; > > nd_mapping->size = memdev->region_size; > > break; > > Why do we need to distinguish NFIT_SPA_VOLATILE vs NFIT_SPA_VCD, i.e. > what happens if something writes to a VCD device? Actually I didn't try to write SPA-VCD device before. Every time I mount it that the system responses read-only: # mount /dev/pmem0 /mnt/ mount: /dev/pmem0 is write-protected, mounting read-only If it can be written, then I think there have no difference between NFIT_SPA_VOLATILE with NFIT_SPA_VCD region. I implemented this patch to treat VCD region as read-only pmem because the pmem region generates /dev/pmem* device that it can be mounted. Maybe I missed. Does NFIT_SPA_VOLATILE region also generate a device in /dev that it can be mounted with filesystem? Then I think treat the VCD region as a read-only VOLATILE region that's also a solution. Thanks a lot! Joey Lee