linux-kernel - Re: [PATCH] MIPS: generic: enable SMP on SMVP systems

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Date:   Fri, 17 Dec 2021 22:12:23 +0000
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     Sander Vanheule <sander@...nheule.net>, linux-mips@...r.kernel.org
Cc:     Paul Burton <paulburton@...nel.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        linux-kernel@...r.kernel.org,
        INAGAKI Hiroshi <musashino.open@...il.com>
Subject: Re: [PATCH] MIPS: generic: enable SMP on SMVP systems



在 2021/12/17 18:39, Sander Vanheule 写道:
> In addition to CPS SMP setups, also try to initialise MT SMP setups with
> multiple VPEs per CPU core. CMP SMP support is not provided as it is
> considered deprecated.
>
> Additionally, rework the code by dropping the err variable and make it
> similar to how other platforms perform this initialisation.
Hi,

Thanks for your patch :-)

However there is a probem that register_vsmp_smp_ops never returns error
if CONFIG_MIPS_MT_SMP is enabled. But generic kernel is supposed to
run on systems with & without MT.

So probably you need:

diff --git a/arch/mips/include/asm/smp-ops.h 
b/arch/mips/include/asm/smp-ops.h
index 65618ff1280c..864aea803984 100644
--- a/arch/mips/include/asm/smp-ops.h
+++ b/arch/mips/include/asm/smp-ops.h
@@ -101,6 +101,9 @@ static inline int register_vsmp_smp_ops(void)
  #ifdef CONFIG_MIPS_MT_SMP
         extern const struct plat_smp_ops vsmp_smp_ops;

+       if (!cpu_has_mipsmt)
+               return -ENODEV;
+
         register_smp_ops(&vsmp_smp_ops);

         return 0;

Thanks.

- Jiaxun