Re: [patch v3 33/36] x86/apic: Save the APIC virtual base address

Sergey Shtylyov
2023-05-09T09:20:49Z

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