diff options
| -rw-r--r-- | kernel/head.S | 52 |
1 files changed, 15 insertions, 37 deletions
diff --git a/kernel/head.S b/kernel/head.S index b175b89..638e5e8 100644 --- a/kernel/head.S +++ b/kernel/head.S @@ -69,46 +69,17 @@ _start_kernel: la a3, hart_lottery li a2, 1 amoadd.w a3, a2, (a3) - beqz a3, .Lhart_proceed -.Lhart_wait: - wfi - j .Lhart_wait + bnez a3, .Lhart_wait -.Lhart_proceed: // Store the hart id as we will tamper with the 'a0' register later when // performing the call to `start_kernel`. la a3, hart_id sw a0, 0(a3) - // Reset all registers except ra, a0, a1. - li sp, 0 + // Explicitely nullify the 'gp' and 'sscratch' registers, as they are a bit + // special but we are not using them. For the rest of the registers, we + // explicitely do not care to reset them. li gp, 0 - li tp, 0 - li t0, 0 - li t1, 0 - li t2, 0 - li s0, 0 - li s1, 0 - li a2, 0 - li a3, 0 - li a4, 0 - li a5, 0 - li a6, 0 - li a7, 0 - li s2, 0 - li s3, 0 - li s4, 0 - li s5, 0 - li s6, 0 - li s7, 0 - li s8, 0 - li s9, 0 - li s10, 0 - li s11, 0 - li t3, 0 - li t4, 0 - li t5, 0 - li t6, 0 csrw sscratch, 0 // Point 'tp' to the init task. The 'tp' register will always point to the @@ -116,7 +87,7 @@ _start_kernel: // printing out messages. la tp, tasks - // Point 'sp' the our general stack. + // Point 'sp' the our global stack. See fbos/sched.h for more details. la sp, stack + STACK_SIZE // The `start_kernel` function requires an argument to be passed, which is @@ -127,6 +98,13 @@ _start_kernel: // Start the kernel. tail start_kernel - // We really shouldn't reach this point, but just in case, just loop - // infinitely here. - j . + // We really shouldn't reach this point. If so, at least mask again all + // interrupts, flush the instruction cache and halt the current hart. + csrw sie, zero + csrw sip, zero + fence.i + + // This is where harts come to die :) +.Lhart_wait: + wfi + j .Lhart_wait |