[PATCH 3/7] riscv: Use NULL as a sentinel value for smp_call_function

[Sean Anderson]

On 9/11/20 4:04 AM, Bin Meng wrote:
> On Tue, Sep 8, 2020 at 2:17 AM Sean Anderson <seanga2 at 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 at gmail.com>
>> ---
>>
>>  arch/riscv/lib/smp.c | 26 ++++++++++++++++++++++----
>>  1 file changed, 22 insertions(+), 4 deletions(-)
>>
> 
> Reviewed-by: Bin Meng <bin.meng at windriver.com>
> 

Per Leo's comments, I will not include this tag in the next revision, as
it uses a different mechanism to accomplish this behavior.

--Sean