On HiFive unleashed board, Why I can’t set IRQ affnity. Following are my commands.
cat /proc/interrupts
CPU1 CPU2 CPU3 CPU4
21: 13 29 34 26 riscv,plic0,c000000 53 eth0
37: 0 0 0 0 riscv,plic0,c000000 32 xilinx-pcie
43: 8 21 29 22 riscv,plic0,c000000 4 10010000.serial
44: 0 0 0 0 riscv,plic0,c000000 5 10011000.serial
45: 0 0 0 0 riscv,plic0,c000000 51 10040000.spi
46: 0 0 0 0 riscv,plic0,c000000 52 10041000.spi
47: 3 11 48 40 riscv,plic0,c000000 6 10050000.spi
48: 0 0 0 0 sifive-gpio 11 spi2.0 cd
echo 8 > /proc/irq/21/smp_affinity
sh: write error: Input/output error
uname -a
Linux buildroot 4.15.0-00044-g2b0aa1d #1 SMP Tue Mar 20 12:18:35 PDT 2018 riscv64 GNU/Linux