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authorLinus Torvalds <torvalds@linux-foundation.org>2019-03-07 13:27:53 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-07 13:27:53 -0800
commitdd1c3ed76f26504621b5ce08b894666aafa38e47 (patch)
treef879aefbbd7871733bc616cb7f73dd5ffca53f44 /Documentation
parent6c3ac1134371b51c9601171af2c32153ccb11100 (diff)
parent60deebe6149a3f02fa6a9fa988dda500effda43f (diff)
Merge tag 'xtensa-20190307' of git://github.com/jcmvbkbc/linux-xtensa
Pull xtensa updates from Max Filippov: - use generic spinlock/rwlock implementations - clean up IPI processing - document boot parameters passing to the kernel - fix get_wchan - various cleanups in time.c, process.c, traps.c and thread_info.h * tag 'xtensa-20190307' of git://github.com/jcmvbkbc/linux-xtensa: xtensa: simplify trap_init xtensa: drop unused definitions xtensa: fix get_wchan xtensa: use generic spinlock/rwlock implementation xtensa: provide xchg for sizes 1 and 2 xtensa: clean up arch/xtensa/kernel/time.c xtensa: SMP: rework IPI processing xtensa: document boot parameter passing
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/xtensa/booting.txt19
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+Passing boot parameters to the kernel.
+
+Boot parameters are represented as a TLV list in the memory. Please see
+arch/xtensa/include/asm/bootparam.h for definition of the bp_tag structure and
+tag value constants. First entry in the list must have type BP_TAG_FIRST, last
+entry must have type BP_TAG_LAST. The address of the first list entry is
+passed to the kernel in the register a2. The address type depends on MMU type:
+- For configurations without MMU, with region protection or with MPU the
+ address must be the physical address.
+- For configurations with region translarion MMU or with MMUv3 and CONFIG_MMU=n
+ the address must be a valid address in the current mapping. The kernel will
+ not change the mapping on its own.
+- For configurations with MMUv2 the address must be a virtual address in the
+ default virtual mapping (0xd0000000..0xffffffff).
+- For configurations with MMUv3 and CONFIG_MMU=y the address may be either a
+ virtual or physical address. In either case it must be within the default
+ virtual mapping. It is considered physical if it is within the range of
+ physical addresses covered by the default KSEG mapping (XCHAL_KSEG_PADDR..
+ XCHAL_KSEG_PADDR + XCHAL_KSEG_SIZE), otherwise it is considered virtual.