From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Enable qspinlock and meet the requirements mentioned in a8ad07e5240c9
("asm-generic: qspinlock: Indicate the use of mixed-size atomics").
RISC-V LR/SC pairs could provide a strong/weak forward guarantee that
depends on micro-architecture. And RISC-V ISA spec has given out
several limitations to let hardware support strict forward guarantee
(RISC-V User ISA - 8.3 Eventual Success of Store-Conditional
Instructions):
We restricted the length of LR/SC loops to fit within 64 contiguous
instruction bytes in the base ISA to avoid undue restrictions on
instruction cache and TLB size and associativity. Similarly, we