linux-kernel - Re: [PATCH v3 0/8] riscv: Unaligned access speed probing fixes and skipping

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Message-ID: <Z8jU2i5d3e4Dv4vk@ghost>
Date: Wed, 5 Mar 2025 14:48:58 -0800
From: Charlie Jenkins <charlie@...osinc.com>
To: Andrew Jones <ajones@...tanamicro.com>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, paul.walmsley@...ive.com,
	palmer@...belt.com, cleger@...osinc.com, alex@...ti.fr,
	Anup Patel <apatel@...tanamicro.com>, corbet@....net
Subject: Re: [PATCH v3 0/8] riscv: Unaligned access speed probing fixes and
 skipping

On Tue, Mar 04, 2025 at 01:00:15PM +0100, Andrew Jones wrote:
> The first six patches of this series are fixes and cleanups of the
> unaligned access speed probing code. The next patch introduces a
> kernel command line option that allows the probing to be skipped.
> This command line option is a different approach than Jesse's [1].
> [1] takes a cpu-list for a particular speed, supporting heterogeneous
> platforms. With this approach, the kernel command line should only
> be used for homogeneous platforms. [1] also only allowed 'fast' and
> 'slow' to be selected. This parameter also supports 'unsupported',
> which could be useful for testing code paths gated on that. The final
> patch adds the documentation.

Why constrain the command line option to homogeneous platforms?

- Charlie

> 
> (I'd be happy to split the fixes from the new skip support if we want to
> discuss the skip support independently, but I want to base on the fixes
> and I'm not sure if patchwork supports Based-on: $MESSAGE_ID/$LORE_URL
> or not at the moment, so I'm just posting together for now in order to
> be able to check for my patchwork green lights!)
> 
> [1] https://lore.kernel.org/linux-riscv/20240805173816.3722002-1-jesse@rivosinc.com/
> 
> Thanks,
> drew
> 
> ---
> v3:
>  - Fix compile when RISCV_PROBE_UNALIGNED_ACCESS is not selected
> 
> v2:
>  - Change to command line option from table
> 
> 
> Andrew Jones (8):
>   riscv: Annotate unaligned access init functions
>   riscv: Fix riscv_online_cpu_vec
>   riscv: Fix check_unaligned_access_all_cpus
>   riscv: Change check_unaligned_access_speed_all_cpus to void
>   riscv: Fix set up of cpu hotplug callbacks
>   riscv: Fix set up of vector cpu hotplug callback
>   riscv: Add parameter for skipping access speed tests
>   Documentation/kernel-parameters: Add riscv unaligned speed parameters
> 
>  .../admin-guide/kernel-parameters.txt         |  16 ++
>  arch/riscv/include/asm/cpufeature.h           |   4 +-
>  arch/riscv/kernel/traps_misaligned.c          |  14 +-
>  arch/riscv/kernel/unaligned_access_speed.c    | 237 +++++++++++-------
>  4 files changed, 168 insertions(+), 103 deletions(-)
> 
> -- 
> 2.48.1
>