Hi, Bin On Mon, Sep 14, 2020 at 10:07:57AM +0800, Bin Meng wrote:
Hi Leo,
On Mon, Sep 14, 2020 at 9:58 AM Leo Liang ycliang@andestech.com wrote:
On Fri, Sep 11, 2020 at 04:04:13PM +0800, Bin Meng wrote:
On Tue, Sep 8, 2020 at 2:17 AM Sean Anderson seanga2@gmail.com wrote:
Some IPIs may already be pending when U-Boot is started. This could be a problem if a secondary hart tries to handle an IPI before the boot hart has initialized the IPI device.
This commit uses NULL as a sentinel for secondary harts so they know when the IPI is initialized, and it is safe to use the IPI API. The smp addr parameter is initialized to NULL by board_init_f_init_reserve. Before this, secondary harts wait in wait_for_gd_init.
This imposes a minor restriction because harts may no longer jump to NULL. However, given that the RISC-V debug device is likely to be located at 0x400, it is unlikely for any RISC-V implementation to have usable ram located at 0x0.
Signed-off-by: Sean Anderson seanga2@gmail.com
arch/riscv/lib/smp.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-)
Reviewed-by: Bin Meng bin.meng@windriver.com
Hi Bin,
There is a series of follow-up discussion on this patch that you might miss reading.
This current patch will cause AE350 to fail booting,
so maybe we should wait until Sean's next patch comes up to consider a reviewed-by tag.
Do we know why AE350 fails to boot with this patch?
When booting with bootm command, boot hart will use smp_call_function(addr, arg0, arg1) to tell other harts to jump to "addr", and other hart will use handle_ipi() to get the "addr".
The address of bbl+kernel payload when booting with AE350 is at 0x0, so the "addr" would be 0x0 that other harts have to jump to.
With this patch
+ if (!ipi->addr) { + pr_err("smp_function cannot be set to 0x0\n"); + return -EINVAL; + }
+ if (!smp_function) + return;
these two code snippets would cause u-boot to hang and thus fail the booting process.
If some big changes are reworked in newer patches, I believe author should remove the tag and re-request the review.
Oh I see! Thanks for the explanation.
Regards, Bin
Best, Leo