在 2020/11/4 14:31, Jinyang He 写道:
Hi, all,
On 11/03/2020 03:12 PM, Tiezhu Yang wrote:
In play_dead function, the whole 64-bit PC mailbox was used as a
indicator
to determine if the master core had written boot jump information.
However, after we introduced CSR mailsend, the hardware will not
guarante
an atomic write for the 64-bit PC mailbox. Thus we have to use the lower
32-bit which is written at the last as the jump indicator instead.
Signed-off-by: Lu Zeng <zen...@loongson.cn>
Signed-off-by: Jun Yi <yi...@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtie...@loongson.cn>
---
v2: No changes
v3: Update the commit message and comment
arch/mips/loongson64/smp.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/mips/loongson64/smp.c b/arch/mips/loongson64/smp.c
index 736e98d..aa0cd72 100644
--- a/arch/mips/loongson64/smp.c
+++ b/arch/mips/loongson64/smp.c
@@ -764,9 +764,10 @@ static void loongson3_type3_play_dead(int
*state_addr)
"1: li %[count], 0x100 \n" /* wait for init
loop */
"2: bnez %[count], 2b \n" /* limit mailbox
access */
" addiu %[count], -1 \n"
- " ld %[initfunc], 0x20(%[base]) \n" /* get PC via
mailbox */
I have some confusion here. Play_dead CPUs is always brought up by
cpu_up().
On Loongson64, it calls loongson3_boot_secondary(). The value of
startargs[0]
is the address of smp_bootstrap() which is in CKSEG0 and a constant
after the
kernel is compiled. That means its value likes 0xffffffff8... and only
the low
32bit is useful. As "lw" is sign-extended, could we replace "ld" with
"lw" simply?
Hi Jinyang,
I'd prefer not to do so. In future we may have kernel running in other
spaces,
(e.g. xkphys), and there is no reason to add a barrier on that without
actual benefit.
I had check PMON firmware and it's also loading the full 64-bit address.
Also to keep consistent, mailbox writing part needs to be refined to
match the
behavior of reading. Otherwise other readers will be confused.
Thus leaving it as is looks much more reasonable.
Thanks.
- Jiaxun
Thanks,
Jinyang
+ " lw %[initfunc], 0x20(%[base]) \n" /* check lower
32-bit as jump indicator */
" beqz %[initfunc], 1b \n"
" nop \n"
+ " ld %[initfunc], 0x20(%[base]) \n" /* get PC (whole
64-bit) via mailbox */
" ld $sp, 0x28(%[base]) \n" /* get SP via
mailbox */
" ld $gp, 0x30(%[base]) \n" /* get GP via
mailbox */
" ld $a1, 0x38(%[base]) \n"
