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b=gtOe0lI4tICmFeXO0VXaSZWun1zD97NtGKzB00Fxz4Ka/Zpm56GHzGCFmpkzXvwya IjgdW5ASTJB+qKa5sg3xhHy+2z3Tif4EUzgG6v2G0AqXAMe/0BNO4ao6/A+PGKiEDt LiunuR042Q+3iJ1jf+LikMpBoAosls+iqBo1ld1uAEuNgD3FyixqBGd1NK8XwlELz8 0aXr47TpsMtDRS4WsQVvIrdjIekWTZVzwY14LA7ppw9cLIVA/gJznyINUg586mqoJr i4bMWj2QqqCUzgdxYWZPl2+vXlMSa8ApBf/xkklnj7o+nTfBb5pP16MUu53RogA7JW PhrukphYxcyLg== Date: Mon, 7 Sep 2026 16:00:19 +0200 From: Thierry Reding To: Vincent Donnefort Cc: Rob Herring , catalin.marinas@arm.com, will@kernel.org, rppt@kernel.org, akpm@linux-foundation.org, sudeep.holla@kernel.org, jenswi@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 02/10] of: reserved_mem: Introduce "ll-map" property Message-ID: References: <20260902104712.2399797-1-vdonnefort@google.com> <20260902104712.2399797-3-vdonnefort@google.com> <20260902172436.GB1440252-robh@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; 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protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v9 02/10] of: reserved_mem: Introduce "ll-map" property MIME-Version: 1.0 On Thu, Sep 03, 2026 at 11:03:12AM +0100, Vincent Donnefort wrote: > On Wed, Sep 02, 2026 at 12:24:36PM -0500, Rob Herring wrote: > > On Wed, Sep 02, 2026 at 11:47:04AM +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 the > > > risk of splitting blocks which, under the break-before-make rule, may > > > trigger page-faults the kernel can't handle. > > >=20 > > > Add an "ll-map" property for reserved-memory regions. When set, it > > > splits the underlying memblock and sets the MEMBLOCK_LLMAP flag. > >=20 > > Where is this documented? Any DT property must have a schema. >=20 > Ack. >=20 > >=20 > > Though I'm not thrilled about more flag properties. Handling all the=20 > > combinations of properties has proven to be painful. Can this be implie= d=20 > > from the compatible string instead? > >=20 > > Rob >=20 > We need this before the kernel direct map has been created (paging_init()= ). >=20 > I would have moved that directly into the driver lend_pool.c, but then it= is > probed too late (unflatten_device_tree()). Any of the node_*() callbacks from struct reserved_mem_ops get called prior to paging_init(), so these could be used to manually set the memblock flags in the corresponding drivers. 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