mainlining shenanigans
6c359eb1dc
On systems where physical memory begins at a non-zero address, defining PHYS_OFFSET (which influences ARCH_PFN_OFFSET) can save us time & memory by avoiding book-keeping for pages from address zero to the start of memory. Some MIPS platforms already make use of this, but with the definition of PHYS_OFFSET being compile-time constant it hasn't been possible to enable this optimization for a kernel which may run on systems with varying physical memory base addresses. Introduce a new Kconfig option CONFIG_MIPS_AUTO_PFN_OFFSET which, when enabled, makes ARCH_PFN_OFFSET a variable & detects it from the boot memory map (which for example may have been populated from DT). The relationship with PHYS_OFFSET is reversed, with PHYS_OFFSET now being based on ARCH_PFN_OFFSET. This is because ARCH_PFN_OFFSET is used far more often, so avoiding the need for runtime calculation gives us a smaller impact on kernel text size (0.1% rather than 0.15% for 64r6el_defconfig). Signed-off-by: Paul Burton <paul.burton@mips.com> Suggested-by: Vladimir Kondratiev <vladimir.kondratiev@intel.com> Patchwork: https://patchwork.linux-mips.org/patch/20048/ Cc: James Hogan <jhogan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.