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Message-ID: <c9efc671-549f-4fb5-96fb-0948badbcef1@arm.com>
Date: Fri, 14 Jun 2024 14:59:16 +0100
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Subject: Re: [PATCH v2 29/35] fs/resctrl: Add boiler plate for external
 resctrl code
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To: Dave Martin <Dave.Martin@arm.com>, x86@kernel.org,
 linux-kernel@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>,
 Reinette Chatre <reinette.chatre@intel.com>,
 Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
 Borislav Petkov <bp@alien8.de>, H Peter Anvin <hpa@zytor.com>,
 Babu Moger <Babu.Moger@amd.com>, shameerali.kolothum.thodi@huawei.com,
 D Scott Phillips OS <scott@os.amperecomputing.com>,
 carl@os.amperecomputing.com, lcherian@marvell.com,
 bobo.shaobowang@huawei.com, "Shaopeng Tan (Fujitsu)"
 <tan.shaopeng@fujitsu.com>, baolin.wang@linux.alibaba.com,
 Jamie Iles <quic_jiles@quicinc.com>, Xin Hao <xhao@linux.alibaba.com>,
 Peter Newman <peternewman@google.com>, dfustini@baylibre.com,
 amitsinght@marvell.com, David Hildenbrand <david@redhat.com>,
 Rex Nie <rex.nie@jaguarmicro.com>
References: <20240426150537.8094-1-Dave.Martin@arm.com>
 <20240426150904.8854-1-Dave.Martin@arm.com>
 <20240426150904.8854-29-Dave.Martin@arm.com>
From: James Morse <james.morse@arm.com>
In-Reply-To: <20240426150904.8854-29-Dave.Martin@arm.com>
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Hi Dave,

On 26/04/2024 16:08, Dave Martin wrote:
> From: James Morse <james.morse@arm.com>
> 
> Add Makefile and Kconfig for fs/resctrl. Add ARCH_HAS_CPU_RESCTRL
> for the common parts of the resctrl interface and make X86_CPU_RESCTRL
> depend on this.


> FYI: Dave Martin, James Morse (et al.):
> 
>  * Review the new Kconfig RESCTRL_FS help text.
> 
>  * Because RESCTRL_FS combines a userspace interface and a kernel
>    library providing services to its own backends, there is a circular
>    dependency between this option and the arch-specific options
>    (CONFIG_X86_RESCTRL and eventually CONFIG_ARM64_MPAM) that
>    nastifies the presentation of these options in Kconfig.
> 
>    Can this be improved?
> 
>    The current situation works, but is not very user-friendly for
>    menuconfig users.

I don't follow what the circular dependency is - Kconfig would bark if there was one.

I agree its odd that you can't disable the filesystem under the filesystem menu - but that
is so that the existing Kconfig symbol name remains the switch for this. It's possible
no-one cares about that...

A more obvious approach would be a switch for the arch hardware feature, that when enabled
allows the filesystem to be selected. This seems overkill as there is only one user.


Thanks,

James