On Tue, 15 Sep 2020 at 20:06, Grant Likely <grant.likely@xxxxxxx> wrote: > > Output from discussion on EBBR issue: > https://github.com/ARM-software/ebbr/issues/52 > > When using the UEFI ABI for booting, the DT memory map is ignored and > instead UEFI GetMemoryMap() is used to find system memory. Also, regions > described in /reserved-memory need to also be added to the UEFI memory > map to protect against overlapping allocations. The patch adds language > to cover both of those cases. > > Signed-off-by: Grant Likely <grant.likely@xxxxxxx> > Cc: Heinrich Schuchardt <xypron.glpk@xxxxxx> > Cc: Ard Biesheuvel <ardb@xxxxxxxxxx> > --- > source/chapter3-devicenodes.rst | 26 +++++++++++++++++++++++--- > source/chapter5-flattened-format.rst | 10 ++++++++++ > source/references.rst | 4 ++++ > 3 files changed, 37 insertions(+), 3 deletions(-) > > diff --git a/source/chapter3-devicenodes.rst b/source/chapter3-devicenodes.rst > index 3043b8a..a78a742 100644 > --- a/source/chapter3-devicenodes.rst > +++ b/source/chapter3-devicenodes.rst > @@ -160,6 +160,12 @@ If the VLE storage attribute is supported, with VLE=0. > .. note:: All other standard properties (section > :ref:`sect-standard-properties`) are allowed but are optional. > > +``/memory`` node and UEFI > +~~~~~~~~~~~~~~~~~~~~~~~~~~ > + > +When booting via [UEFI]_, the system memory map is obtained via the > +GetMemoryMap() UEFI boot time service as defined in [UEFI]_ § 7.2, > +and if present, the OS must ignore any ``/memory`` nodes. > > ``/memory`` Examples > ~~~~~~~~~~~~~~~~~~~~ > @@ -308,12 +314,12 @@ is ignored. > Usage legend: R=Required, O=Optional, OR=Optional but Recommended, SD=See Definition > ======================================================================================================= > > -.. note:: All other standard properties (section > - :ref:`sect-standard-properties`) are allowed but are optional. > - > The ``no-map`` and ``reusable`` properties are mutually exclusive and both must > not be used together in the same node. > > +Dynamic reserved memory regions must not be listed in the [UEFI]_ memory map > +because they are allocated by the OS after exiting firmware boot services. > + > Linux implementation notes: > > - If a ``linux,cma-default`` property is present, then Linux will use the > @@ -341,6 +347,20 @@ nodes by adding a ``memory-region`` property to the device node. > Usage legend: R=Required, O=Optional, OR=Optional but Recommended, SD=See Definition > ======================================================================================================= > > +.. _sect-reserved-memory-uefi: > + > +``/reserved-memory`` and UEFI > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > +When booting via [UEFI]_, static ``/reserved-memory`` regions must > +also be listed in the system memory map obtained via the GetMemoryMap() > +UEFI boot time service as defined in [UEFI]_ § 7.2. > +The reserved memory regions need to be included in the UEFI memory map to > +protect against allocations by UEFI applications. > + > +Reserved regions with the ``no-map`` property must be listed in the memory > +map with type ``EfiReservedMemoryType``. > +All other reserved regions must be listed with type ``EfiBootServicesData``. > + > ``/reserved-memory`` Example > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > diff --git a/source/chapter5-flattened-format.rst b/source/chapter5-flattened-format.rst > index 28e5bd4..b1e2b8b 100644 > --- a/source/chapter5-flattened-format.rst > +++ b/source/chapter5-flattened-format.rst > @@ -234,6 +234,16 @@ reservation block as a whole, shall be located at an 8-byte aligned > offset from the beginning of the devicetree blob (see section > :ref:`sect-fdt-alignment`). > > +Memory Reservation Block and UEFI > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + > +As with the ``/reserved-memory`` node (section :ref:`sect-reserved-memory-uefi`), > +when booting via [UEFI]_ entries in the Memory Reservation Block must also be > +listed in the system memory map obtained via the GetMemoryMap() to protect against > +allocations by UEFI applications. > +The memory reservation block entries should be listed with type > +``EfiBootServicesData``. > + Didn't we just agree this should be EfiReservedMemoryType ? > .. _sect-fdt-structure-block: > > Structure Block > diff --git a/source/references.rst b/source/references.rst > index 961fa20..8400e96 100644 > --- a/source/references.rst > +++ b/source/references.rst > @@ -23,3 +23,7 @@ > .. [EPAPR] *Power.org Standard for Embedded Power Architecture > Platform Requirements*, power.org, 2011, > https://www.power.org/documentation/power-org-standard-for-embedded-power-architecture-platform-requirements-epapr-v1-1-2/ > + > +.. [UEFI] `Unified Extensable Firmware Interface Specification v2.8 Errata A > + <https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_A_Feb14.pdf>`_, > + February 2020, `UEFI Forum <http://www.uefi.org>`_ > -- > 2.20.1 >
