b1ce9716f3
Use 0 as the align parameter in memblock_find_in_range() is
incorrect when we reserve memory for Crash kernel.
The environment as follows:
[ 0.000000] MIPS: machine is loongson,loongson64c-4core-rs780e
...
[ 1.951016] crashkernel=64M@128M
The warning as follows:
[ 0.000000] Invalid memory region reserved for crash kernel
And the iomem as follows:
00200000-0effffff : System RAM
04000000-0484009f : Kernel code
048400a0-04ad7fff : Kernel data
04b40000-05c4c6bf : Kernel bss
1a000000-1bffffff : pci@1a000000
...
The align parameter may be finally used by round_down() or round_up().
Like the following call tree:
mips-next: mm/memblock.c
memblock_find_in_range
└── memblock_find_in_range_node
├── __memblock_find_range_bottom_up
│ └── round_up
└── __memblock_find_range_top_down
└── round_down
\#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
\#define round_down(x, y) ((x) & ~__round_mask(x, y))
\#define __round_mask(x, y) ((__typeof__(x))((y)-1))
The round_down(or round_up)'s second parameter must be a power of 2.
If the second parameter is 0, it both will return 0.
Use 1 as the parameter to fix the bug and the iomem as follows:
00200000-0effffff : System RAM
04000000-0484009f : Kernel code
048400a0-04ad7fff : Kernel data
04b40000-05c4c6bf : Kernel bss
08000000-0bffffff : Crash kernel
1a000000-1bffffff : pci@1a000000
...
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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.
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.