From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932758AbdBHRl2 (ORCPT ); Wed, 8 Feb 2017 12:41:28 -0500 Received: from mail-wm0-f45.google.com ([74.125.82.45]:34148 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753568AbdBHRkz (ORCPT ); Wed, 8 Feb 2017 12:40:55 -0500 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (1.0) Subject: Re: [PATCH v3 06/10] arm64: efi: add EFI stub From: Ard Biesheuvel X-Mailer: iPhone Mail (14D27) In-Reply-To: <20170208170305.GI15459@leverpostej> Date: Wed, 8 Feb 2017 17:40:35 +0000 Cc: Timur Tabi , linux-efi@vger.kernel.org, Catalin Marinas , lkml , Leif Lindholm , Mark Salter , "linux-arm-kernel@lists.infradead.org" Message-Id: <8792A751-3557-4D81-921B-F544EEE38811@linaro.org> References: <1396637113-22790-1-git-send-email-leif.lindholm@linaro.org> <1396637113-22790-7-git-send-email-leif.lindholm@linaro.org> <73a460e5-98f5-86c2-142f-a9a084ee0203@codeaurora.org> <20170208170305.GI15459@leverpostej> To: Mark Rutland Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v18HfVLR022084 > On 8 Feb 2017, at 17:03, Mark Rutland wrote: > >> On Wed, Feb 08, 2017 at 10:35:02AM -0600, Timur Tabi wrote: >> On 02/08/2017 10:29 AM, Ard Biesheuvel wrote: >>>>>>> + status = handle_cmdline_files(sys_table, image, cmdline_ptr, >>>>>>> + "initrd=", dram_base + SZ_512M, >>>>>>> + (unsigned long *)&initrd_addr, >>>>>>> + (unsigned long *)&initrd_size); >>>>> >>>>> So I know this patch is almost three years old, but why is there a >>>>> 512M limit on the initrd size? >>>>> >>> How do you reckon this constitutes a limit? >> >> handle_cmdline_files() calls efi_high_alloc() with that limit. I'm >> still trying to understand all the details myself, but apparently >> our firmware and initrd need to fit within the first 512MB because >> of dram_base + SZ_512M. When we change "dram_base + SZ_512M" to >> "~0", everything works. > > Just to check, how big is that initrd? > > I guess it's possible that there simply isn't sufficient contiguous free > memory in that range, even if the initrd isn't that large. Can you share > the EFI memory map dump from booting with efi=debug? > > We originally needed to restrict this to ensure that the kernel could > map the initrd (and I think the 512M restriction specifically was > inherited from the DTB mapping restriction). Since then, we have relaxed > things in the kernel, and today Documentation/arm64/booting.txt says: > > If an initrd/initramfs is passed to the kernel at boot, it must > reside entirely within a 1 GB aligned physical memory window of > up to 32 GB in size that fully covers the kernel Image as well. > > ... so I think the EFI stub should be able to take advantage of that > relaxation. > > Ard? > Interestingly enough, this code originates on 32-bit ARM, where the linear mapping is only 800 MB so I suspect that may have something to do with it. I agree the stub should simply follow the rules laid out in booting.txt. I think nobody hit this because it is usually GRUB that loads the initrd not the EFI stub