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To: Russell King <rmk+kernel@armlinux.org.uk>, linux-pm@vger.kernel.org,
 loongarch@lists.linux.dev, linux-acpi@vger.kernel.org,
 linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org,
 kvmarm@lists.linux.dev, x86@kernel.org, linux-csky@vger.kernel.org,
 linux-doc@vger.kernel.org, linux-ia64@vger.kernel.org,
 linux-parisc@vger.kernel.org
Cc: Salil Mehta <salil.mehta@huawei.com>, Jean-Philippe Brucker
 <jean-philippe@linaro.org>, jianyong.wu@arm.com, justin.he@arm.com, James
 Morse <james.morse@arm.com>, Greg Kroah-Hartman
 <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rafael@kernel.org>,
 Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt
 <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>
Subject: Re: [PATCH 08/21] drivers: base: Implement weak arch_unregister_cpu()
In-Reply-To: <E1r5R3H-00CszC-2n@rmk-PC.armlinux.org.uk>
References: <ZVyz/Ve5pPu8AWoA@shell.armlinux.org.uk>
 <E1r5R3H-00CszC-2n@rmk-PC.armlinux.org.uk>
Date: Fri, 01 Dec 2023 12:06:31 +0100
Message-ID: <87sf4mxjuw.ffs@tglx>
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On Tue, Nov 21 2023 at 13:44, Russell King wrote:
> ---
> An open question remains from the RFC v2 posting: should we provide a
> __weak stub for !HOTPLUG_CPU as well, since in later patches ACPI may
> reference this if the compiler doesn't optimise as we expect?

You mean:

extern void foo(void);

    if (!IS_ENABLED(CONFIG_FOO))
    	foo();

The kernel uses this pattern for years and if someday a compiler starts
to fail to eliminate the call to 'foo()' for CONFIG_FOO=n then you
already get hundreds linkage fails today.

So adding one more in later patches won't matter much :)