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Subject: Re: [patch v3 33/36] x86/apic: Save the APIC virtual base address
To:     Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>
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References: <20230508181633.089804905@linutronix.de>
 <20230508185219.070274100@linutronix.de>
From:   Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
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Date:   Tue, 9 May 2023 12:20:06 +0300
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Hello!

On 5/8/23 10:44 PM, Thomas Gleixner wrote:

> From: Thomas Gleixner <tglx@linutronix.de>
> 
> For parallel CPU brinugp it's required to read the APIC ID in the low level
> startup code. The virtual APIC base address is a constant because its a
> fix-mapped address. Exposing that constant which is composed via macros to
> assembly code is non-trivial dues to header inclusion hell.

   s/dues/due/?

> Aside of that it's constant only because of the vsyscall ABI
> requirement. Once vsyscall is out of the picture the fixmap can be placed
> at runtime.
> 
> Avoid header hell, stay flexible and store the address in a variable which
> can be exposed to the low level startup code.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Tested-by: Michael Kelley <mikelley@microsoft.com>

[...]

MBR, Sergey