From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EC3D8521219; Tue, 8 Sep 2026 09:19:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788859142; cv=none; b=NXDaDROnxJfJ7JIPQ/Ae60TQUKK533LmMdQmfpY8tc08VcT/WVuK5vED6BR/G2LOE6n3cCw4Vt/4NyfYQBdByGkaljB5fxaI2Xvb8N5E3NJPVASim20FDsgaK7qb++9lLDnbZJyr5TO52NVmNOkeRjeJ+FbfMGzn5f9oAFmtRn0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788859142; c=relaxed/simple; bh=jC952bHmiBBRZiJqd17i/7x1m+YVL1dngpkL95OZce4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MyeAY3euvx8n4vbXuFObTVI/ubkOgE1MRDQ8bcjHg1cMOif6fmmHSHcGwB1LJ1TxnQ9f2m8NIsZvKazT9dSvVdCFHBRvsF+hAWO5Se+GQijA9hfymHO3mUM56sQhPV+sEyTcOoUJWCJ9eDiWlDegP7BnF0irZA18ascnyVhO+5Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFB201F00A3D; Tue, 8 Sep 2026 09:18:59 +0000 (UTC) Date: Tue, 8 Sep 2026 11:18:53 +0200 From: Thierry Reding To: Mike Rapoport Cc: Vincent Donnefort , catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, sudeep.holla@kernel.org, jenswi@kernel.org, robh@kernel.org, mark.rutland@arm.com, sumit.garg@kernel.org, ardb@kernel.org, david@kernel.org, danielmentz@google.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, op-tee@lists.trustedfirmware.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 01/10] memblock: Introduce MEMBLOCK_LLMAP Message-ID: References: <20260902104712.2399797-1-vdonnefort@google.com> <20260902104712.2399797-2-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ajtkrsfbue5mdrla" Content-Disposition: inline In-Reply-To: --ajtkrsfbue5mdrla Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v9 01/10] memblock: Introduce MEMBLOCK_LLMAP MIME-Version: 1.0 On Tue, Sep 08, 2026 at 10:40:16AM +0300, Mike Rapoport wrote: > On Mon, Sep 07, 2026 at 10:50:12AM +0100, Vincent Donnefort wrote: > > On Sun, Sep 06, 2026 at 10:33:11PM +0300, Mike Rapoport wrote: > > > On Wed, Sep 02, 2026 at 11:47:03AM +0100, Vincent Donnefort wrote: > > > > Keeping last-level mappings is interesting on some architectures as= it > > > > allows mapping/unmapping pages from the kernel direct map without t= he > > > > risk of splitting blocks which, under the break-before-make rule, m= ay > > > > trigger page-faults the kernel can't handle. > > > >=20 > > > > However, mapping the entire direct map at PTE-level is costly. So > > > > instead, create a new memblock flag MEMBLOCK_LLMAP to enable the sy= stem > > >=20 > > > I believe MEMBLOCK_PTE_MAP sounds more descriptive. > >=20 > > The idea was to have something close from NOMAP, to emphasis it is one = or the > > other. But PTE_MAP sounds good too. >=20 > Could be PTEMAP if you prefer. > My point was that unlike PTE, "LL" is not perceived as last-level, it > should be looked up. We were discussing the concept of enabling entire block mappings to be removed at once from the linear map, so at that point "PTE"MAP may no longer be accurate. I imagine that in some scenarios we might be able to go to PUD mappings for something like VPR (say systems with a fair amount of system memory and we want to carve out 4 GiB for VPR, split into four 1 GiB chunks). Thierry --ajtkrsfbue5mdrla Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAmqf0voACgkQ3SOs138+ s6EFrw//chVhQxMWtCxc+JK5ON8AveSiC1Dhl62Q8IhDi1Pr5AWMxC7K8li30qSy 0r+vt3im7cyLAkLE4+kAZXtHcCV1288tZZErEnuotKkDkGDaDExBqr5yHlPseVq0 2ekvvxz7mSRh5Wfxn5Tq+MYQcwUYACknVRhGjuplsa05oSZA7GWbViEHFVP25/Pq 14BkCYqXXj/NfSceq84ukKSePfpEG9Jrmnl7Ey73eyGHNeRvziLQC7qd9MuHwiqp Jn9Geb830b3ufqnZK23k5BuEp/+lAGTkflZGTlEM5A6yTIEnvfVtpimFwGtHret9 L0HZ/xg087+Wj7Kdgu/VjdftAzj81qqnKT8dpnGWH4SwsTLtcRDqxpNZatKlVJsF NJG1Q8yBEtB+KIIiSK/00K2im6bSroJoGbTljdLQVi/hjBkQuDHtugvyyycXYc5y cLPWS6i+0eG+IWvM+wGH7zWT9kvJeyYWh8jH4qk/J0sTkVlz5IY25AOerpGGdx4S slR0PSPzLmGm/uHHm6PpuJK8vjqKJkGmsLiXQ5XkrUgmOG8EkWHG9Uzx358zDsQg AYe3yJ0IiuCS2fketV+KzHy7VqFU3tC9kgkyrIO3PJSJLSVSeTVFNJ3WTUJTEBBb ztr3XvA0Jm7feoWXZzfW9fwBYnq+5ey+M+KDQ6qsCZGpgY7FCeo= =5bgM -----END PGP SIGNATURE----- --ajtkrsfbue5mdrla--