From 441848282c59038b6e9a57b233ac6a9449430648 Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Thu, 8 Oct 2020 09:24:20 -0500 Subject: dt: Remove booting-without-of.rst booting-without-of.rst is an ancient document that first outlined Flattened DeviceTree on PowerPC initially. The DT world has evolved a lot in the 15 years since and booting-without-of.rst is pretty stale. The name of the document itself is confusing if you don't understand the evolution from real 'OpenFirmware'. Most of what booting-without-of.rst contains is now in the DT specification (which evolved out of the ePAPR). The few things that weren't documented in the DT specification are now. All that remains is the boot entry details, so let's move these to arch specific documents. The exception is arm which already has the same details documented. Cc: Frank Rowand Cc: Mauro Carvalho Chehab Cc: Geert Uytterhoeven Cc: Michael Ellerman Cc: Thomas Bogendoerfer Cc: Jonathan Corbet Cc: Paul Mackerras Cc: Yoshinori Sato Cc: Rich Felker Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-mips@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-sh@vger.kernel.org Acked-by: Benjamin Herrenschmidt Acked-by: Borislav Petkov Acked-by: Michael Ellerman (powerpc) Signed-off-by: Rob Herring --- Documentation/mips/booting.rst | 28 ++++++++++++++++++++++++++++ Documentation/mips/index.rst | 1 + 2 files changed, 29 insertions(+) create mode 100644 Documentation/mips/booting.rst (limited to 'Documentation/mips') diff --git a/Documentation/mips/booting.rst b/Documentation/mips/booting.rst new file mode 100644 index 000000000000..7c18a4eab48b --- /dev/null +++ b/Documentation/mips/booting.rst @@ -0,0 +1,28 @@ +.. SPDX-License-Identifier: GPL-2.0 + +BMIPS DeviceTree Booting +------------------------ + + Some bootloaders only support a single entry point, at the start of the + kernel image. Other bootloaders will jump to the ELF start address. + Both schemes are supported; CONFIG_BOOT_RAW=y and CONFIG_NO_EXCEPT_FILL=y, + so the first instruction immediately jumps to kernel_entry(). + + Similar to the arch/arm case (b), a DT-aware bootloader is expected to + set up the following registers: + + a0 : 0 + + a1 : 0xffffffff + + a2 : Physical pointer to the device tree block (defined in chapter + II) in RAM. The device tree can be located anywhere in the first + 512MB of the physical address space (0x00000000 - 0x1fffffff), + aligned on a 64 bit boundary. + + Legacy bootloaders do not use this convention, and they do not pass in a + DT block. In this case, Linux will look for a builtin DTB, selected via + CONFIG_DT_*. + + This convention is defined for 32-bit systems only, as there are not + currently any 64-bit BMIPS implementations. diff --git a/Documentation/mips/index.rst b/Documentation/mips/index.rst index d5ad8c00f0bd..35cceea4e8bc 100644 --- a/Documentation/mips/index.rst +++ b/Documentation/mips/index.rst @@ -8,6 +8,7 @@ MIPS-specific Documentation :maxdepth: 2 :numbered: + booting ingenic-tcu .. only:: subproject and html -- cgit v1.2.3-59-g8ed1b