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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 <frowand.list@gmail.com> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Paul Mackerras <paulus@samba.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> 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 <benh@kernel.crashing.org> Acked-by: Borislav Petkov <bp@suse.de> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Signed-off-by: Rob Herring <robh@kernel.org>
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21 lines
938 B
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.. SPDX-License-Identifier: GPL-2.0
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DeviceTree Booting
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------------------
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There is one single 32bit entry point to the kernel at code32_start,
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the decompressor (the real mode entry point goes to the same 32bit
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entry point once it switched into protected mode). That entry point
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supports one calling convention which is documented in
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Documentation/x86/boot.rst
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The physical pointer to the device-tree block is passed via setup_data
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which requires at least boot protocol 2.09.
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The type filed is defined as
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#define SETUP_DTB 2
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This device-tree is used as an extension to the "boot page". As such it
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does not parse / consider data which is already covered by the boot
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page. This includes memory size, reserved ranges, command line arguments
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or initrd address. It simply holds information which can not be retrieved
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otherwise like interrupt routing or a list of devices behind an I2C bus.
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