From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54AB4C433EF for ; Wed, 12 Jan 2022 18:05:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 863A26B01F3; Wed, 12 Jan 2022 13:05:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 812FD6B01F4; Wed, 12 Jan 2022 13:05:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6B4D96B01F5; Wed, 12 Jan 2022 13:05:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 46B386B01F3 for ; Wed, 12 Jan 2022 13:05:54 -0500 (EST) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id B7C66181C5562 for ; Wed, 12 Jan 2022 18:05:53 +0000 (UTC) X-FDA: 79022413386.08.EECA14C Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf09.hostedemail.com (Postfix) with ESMTP id 49206140013 for ; Wed, 12 Jan 2022 18:05:53 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D9C646199F; Wed, 12 Jan 2022 18:05:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0DDABC36AE5; Wed, 12 Jan 2022 18:05:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642010751; bh=jeMAXsD0RQlHdtuX5ty1VxBTZG6coZYil0NxX+mHVXQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rKRlZc1mzdvVLDPimEh2XnSL8qxBf/33jwUf4yenZgE3OzOhcsRRweFgWg/iuckRY clYXBJqANQ0mO8U6PXE0O8QefvoYrqyD8mhvN+Vh0scBpgefaSNjdiegPiEh7TqmNw PYBwjIRX+4K0kD1Adwzevv6CnYI35vPhUSYKm9IAr+DaBM3PJaLzXcfauR2tbp3ORX O8k9JGDFGs/m1s1bsVs/sXXL1vU+0cv5PkvmqkTJG0D44P1ra12fGVBdccnB4pWbs5 IuynmG80HNYhcx75MCn/e0PP7lKe9S23QhRF/safDSz0jzs9FN604K1pLkBJlo7yxp zEWKF0EHBSMpw== Date: Wed, 12 Jan 2022 20:05:41 +0200 From: Mike Rapoport To: Frank van der Linden Cc: linux-arm-kernel@lists.infradead.org, robh+dt@kernel.org, frowand.list@gmail.com, ardb@kernel.org, linux-mm@kvack.org, devicetree@vger.kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org, geert+renesas@glider.be Subject: Re: [PATCH 1/3] memblock: define functions to set the usable memory range Message-ID: References: <20220110210809.3528-1-fllinden@amazon.com> <20220110210809.3528-2-fllinden@amazon.com> <20220111204441.GA36458@dev-dsk-fllinden-2c-d7720709.us-west-2.amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220111204441.GA36458@dev-dsk-fllinden-2c-d7720709.us-west-2.amazon.com> X-Rspamd-Queue-Id: 49206140013 X-Stat-Signature: p3xbeh15odkzbijxr5qbz68gquwyqq4m Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=rKRlZc1m; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf09.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org X-Rspamd-Server: rspam02 X-HE-Tag: 1642010753-145946 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jan 11, 2022 at 08:44:41PM +0000, Frank van der Linden wrote: > On Tue, Jan 11, 2022 at 12:31:58PM +0200, Mike Rapoport wrote: > > > --- a/include/linux/memblock.h > > > +++ b/include/linux/memblock.h > > > @@ -481,6 +481,8 @@ phys_addr_t memblock_reserved_size(void); > > > phys_addr_t memblock_start_of_DRAM(void); > > > phys_addr_t memblock_end_of_DRAM(void); > > > void memblock_enforce_memory_limit(phys_addr_t memory_limit); > > > +void memblock_set_usable_range(phys_addr_t base, phys_addr_t size); > > > +void memblock_enforce_usable_range(void); > > > void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size); > > > void memblock_mem_limit_remove_map(phys_addr_t limit); > > > > We already have 3 very similar interfaces that deal with memory capping. > > Now you suggest to add fourth that will "generically" solve a single use > > case of DT, EFI and kdump interaction on arm64. > > > > Looks like a workaround for a fundamental issue of incompatibility between > > DT and EFI wrt memory registration. > > Yep, I figured this would be the main argument against this - arm64 > already added several other more-or-less special cased interfaces over > time. > > I'm more than happy to solve this in a different way. > > What would you suggest: > > 1) Try to merge the similar interfaces in to one. This could be a nice cleanup regardless of how we handle "linux,usable-memory-range". > 2) Just deal with it at a lower (arm64) level? Probably it will be the simplest solution in the short term. > 3) Some other way? I'm not expert enough on DT and EFI to see how they communicate the linux,usable-memory-range property. One thought I have is since we already create a DT for kexec/kdump why can't we add some data to EFI memory description similar to linux,usable-memore-range? Another thing is, if we could presume that DT and EFI are consistent in their view what is the span of the physical memory, we could drop memblock_remove(EVERYTHIING) and early_init_dt_add_memory_arch() from efi_init::reserve_regions() and then the loop over EFI memory descriptors will only take care of reserved and nomap regions. > Thanks, > > - Frank > -- Sincerely yours, Mike.