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From: Sean Anderson <seanga2@gmail.com>
To: u-boot@lists.denx.de
Subject: [PATCH 3/7] riscv: Use NULL as a sentinel value for smp_call_function
Date: Mon, 14 Sep 2020 10:05:28 -0400	[thread overview]
Message-ID: <12db0e9b-27a1-eb3c-f35e-8f2aa94cda01@gmail.com> (raw)
In-Reply-To: <CAEUhbmVFf5OdSrwYoCoMbbZeUOhm+ZQvWanrvpvE_M0D6Ri57g@mail.gmail.com>


On 9/11/20 4:04 AM, 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>
> 

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

  parent reply	other threads:[~2020-09-14 14:05 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-07 18:16 [PATCH 0/7] riscv: Correctly handle IPIs already pending upon boot Sean Anderson
2020-09-07 18:16 ` [PATCH 1/7] Revert "riscv: Clear pending interrupts before enabling IPIs" Sean Anderson
2020-09-09  7:50   ` Rick Chen
2020-09-09 10:23     ` Sean Anderson
2020-09-10  6:39       ` Rick Chen
2020-09-10 10:18         ` Sean Anderson
2020-09-11  7:38   ` Bin Meng
2020-09-11 10:22     ` Sean Anderson
2020-09-11 14:45       ` Bin Meng
2020-09-11 18:30         ` Sean Anderson
2020-09-14  3:10           ` Rick Chen
2020-09-14 12:45             ` Sean Anderson
2020-09-07 18:16 ` [PATCH 2/7] riscv: Match memory barriers between send_ipi_many and handle_ipi Sean Anderson
2020-09-11  7:45   ` Bin Meng
2020-09-07 18:16 ` [PATCH 3/7] riscv: Use NULL as a sentinel value for smp_call_function Sean Anderson
2020-09-09  8:33   ` Rick Chen
2020-09-09  9:01     ` Rick Chen
2020-09-09 10:16       ` Sean Anderson
2020-09-09 10:26         ` Heinrich Schuchardt
2020-09-09 10:36           ` Sean Anderson
2020-09-10  8:09         ` Rick Chen
2020-09-14  3:21         ` Rick Chen
2020-09-11  8:04   ` Bin Meng
2020-09-14  1:58     ` Leo Liang
2020-09-14  2:07       ` Bin Meng
2020-09-14  6:10         ` Leo Liang
2020-09-14  6:15           ` Bin Meng
2020-09-14 14:05     ` Sean Anderson [this message]
2020-09-07 18:16 ` [PATCH 4/7] riscv: Clear pending IPIs on initialization Sean Anderson
2020-09-14  2:08   ` Bin Meng
2020-09-07 18:16 ` [PATCH 5/7] riscv: Add fence to available_harts_lock Sean Anderson
2020-09-10  3:26   ` Rick Chen
2020-09-11 10:39     ` Sean Anderson
2020-09-11 14:47   ` Bin Meng
2020-09-07 18:16 ` [PATCH 6/7] riscv: Ensure gp is NULL or points to valid data Sean Anderson
2020-09-14  5:25   ` Bin Meng
2020-09-14 13:03     ` Sean Anderson
2020-09-14 13:27       ` Sean Anderson
2020-09-07 18:16 ` [PATCH 7/7] riscv: Add some comments to start.S Sean Anderson
2020-09-14  5:26   ` Bin Meng
2020-09-09  2:02 ` [PATCH 0/7] riscv: Correctly handle IPIs already pending upon boot Rick Chen
2020-09-09  2:38   ` Sean Anderson
2020-09-09  2:44     ` Sean Anderson
2020-09-10  7:08     ` Rick Chen
2020-09-10 10:49       ` Sean Anderson

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