Commit a4c5b01c authored by Vladimir Murzin's avatar Vladimir Murzin

ARM: Allow ARCH_MULTIPLATFORM to be selected for NOMMU

With this patch applied potentially any platform can be built in NOMMU
configurations if CONFIG_EXPERT is selected. However, there is no
guarantee that platform can successfully run such Image. So the main
motivation behind of this patch:
- bring build coverage for NOMMU configurations
- allow known working NOMMU platforms (like R-class) to be used
- pave a way to add support for single address space (aka 1:1 mapping)
  for MMU platforms, so they can be usable in NOMMU configurations

Cc: Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Vladimir Murzin's avatarVladimir Murzin <vladimir.murzin@arm.com>
parent 4f88be1d
......@@ -327,9 +327,9 @@ choice
config ARCH_MULTIPLATFORM
bool "Allow multiple platforms to be selected"
depends on MMU
depends on MMU || EXPERT
select ARM_HAS_SG_CHAIN
select ARM_PATCH_PHYS_VIRT
select ARM_PATCH_PHYS_VIRT if MMU
select AUTO_ZRELADDR
select CLKSRC_OF
select COMMON_CLK
......@@ -339,6 +339,23 @@ config ARCH_MULTIPLATFORM
select PCI_DOMAINS if PCI
select SPARSE_IRQ
select USE_OF
help
Please, read carefully if you've selected CONFIG_MMU=n!
Multiplatform with !MMU configuration *is not* meant that
kernel built to support every platform will boot on them. It
is because physical address space layouts (particularly where
RAM is located) are different between platforms and there is
no MMU to work that around.
You must specify where RAM start (via DRAM_BASE config
option) and appropriate size of RAM (via DRAM_SIZE config
option) which are valid for the platform you are building
for.
This feature is *EXPERIMENTAL*, please, consider building
with CONFIG_MMU=y unless you know what you do or want to
help with testing.
config ARM_SINGLE_ARMV7M
bool "ARMv7-M based platforms (Cortex-M0/M3/M4)"
......
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