From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id E4FF581D6A for ; Fri, 20 Jan 2017 08:44:34 -0800 (PST) Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 836CD3D975; Fri, 20 Jan 2017 16:44:35 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-116-71.phx2.redhat.com [10.3.116.71]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v0KGiY2B007158; Fri, 20 Jan 2017 11:44:34 -0500 To: Ard Biesheuvel References: <9fdd45fb-710c-cd62-d65e-fe541037a069@redhat.com> Cc: edk2-devel-01 From: Laszlo Ersek Message-ID: <098a2187-e417-a293-766d-3d383dcb5bed@redhat.com> Date: Fri, 20 Jan 2017 17:44:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <9fdd45fb-710c-cd62-d65e-fe541037a069@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 20 Jan 2017 16:44:35 +0000 (UTC) Subject: Re: [QUESTION] reservation of pool allocations performed during PEI X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 20 Jan 2017 16:44:35 -0000 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit On 01/20/17 17:38, Laszlo Ersek wrote: > On 01/20/17 17:05, Ard Biesheuvel wrote: >> After a recent change to the AArch64 page table code, the root table >> of the page tables is allocated using AllocatePool() rather than >> AllocatePages() if its size is much smaller than a page. E.g., when >> using 40 bits of translation, the root table only takes up 16 bytes >> >> However, what I have noticed is that pool allocations made during PEI >> are listed as available memory in the EFI memory map (using memmap in >> the UEFI Shell). Is this expected? Is it part of the contract that >> AllocatePool() allocations are lost when entering DXE? > > Pool allocations in PEI are satisfied with HOBs (and therefore the pool > allocation sizes are limited to ~64KB). > > In addition, soon after permanent PEI RAM is installed, objects from the > temporary SEC/PEI heap are moved there (this is called "temporary RAM > migration"). This includes the migration of the full HOB list, including > those that were used to satisfy pool allocations prior to RAM migration. > > If you want to allocate memory in PEI that is to survive in-place into > DXE and later, I can think of two ways: > > - Call AllocatePages. This will only work after permanent PEI RAM has > been installed (so you might want to make the PEIM performing the call > dependent on gEfiPeiMemoryDiscoveredPpiGuid, with a DEPEX). The > allocation will be carved out of the permanent PEI RAM. > > - Allocate a region (a whole multiple of pages) outside of the permanent > PEI RAM, but in a spot that will later on be backed by system memory > (due to a system memory resource descriptor HOB produced in PEI, or due > to a GCD memory space addition during DXE). The way to perform this kind > of allocation is simply to produce a memory allocation HOB, covering the > range in question. This works even before the installation of permanent > PEI RAM. > > ... I hope I remembered most of this stuff right. You mention that AllocatePages() used to work in the same spot; that means that it occurs after permanent PEI RAM installation, hence (likely -- there's a very small gap) after temoprary RAM migration too. Hence, the HOBs should have been migrated to permanent PEI RAM already. I very vaguely recall / suspect that HOBs are again moved when DXE starts up?... Should check in the PI spec, but it's Friday... I recommend sticking with AllocatePages(), if it can work in the spot in question; otherwise a memalloc HOB. Laszlo