Re: [PATCH v6 13/13] riscv: Add qspinlock support

From: Conor Dooley
Date: Thu Nov 28 2024 - 07:58:15 EST


On Sun, Nov 03, 2024 at 03:51:53PM +0100, Alexandre Ghiti wrote:
> In order to produce a generic kernel, a user can select
> CONFIG_COMBO_SPINLOCKS which will fallback at runtime to the ticket
> spinlock implementation if Zabha or Ziccrse are not present.
>
> Note that we can't use alternatives here because the discovery of
> extensions is done too late and we need to start with the qspinlock
> implementation because the ticket spinlock implementation would pollute
> the spinlock value, so let's use static keys.
>
> This is largely based on Guo's work and Leonardo reviews at [1].
>
> Link: https://lore.kernel.org/linux-riscv/20231225125847.2778638-1-guoren@xxxxxxxxxx/ [1]
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxx>
> Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>

This patch (now commit ab83647fadae2 ("riscv: Add qspinlock support"))
breaks boot on polarfire soc. It dies before outputting anything to the
console. My .config has:

# CONFIG_RISCV_TICKET_SPINLOCKS is not set
# CONFIG_RISCV_QUEUED_SPINLOCKS is not set
CONFIG_RISCV_COMBO_SPINLOCKS=y

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