linux-kernel - Re: [PATCH v2 1/2] x86/of: Add support for boot time interrupt delivery mode configuration

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Date:   Wed, 16 Nov 2022 12:42:28 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Rahul Tanwar <rtanwar@...linear.com>
Cc:     devicetree@...r.kernel.org, robh@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, linux-kernel@...r.kernel.org, hpa@...or.com,
        alan@...rguk.ukuu.org.uk, dirk.brandewie@...il.com,
        grant.likely@...retlab.ca, sodaville@...utronix.de,
        devicetree-discuss@...ts.ozlabs.org, linux-lgm-soc@...linear.com
Subject: Re: [PATCH v2 1/2] x86/of: Add support for boot time interrupt
 delivery mode configuration

On Wed, Nov 16, 2022 at 06:28:20PM +0800, Rahul Tanwar wrote:
> Presently, init/boot time interrupt delivery mode is enumerated
> only for ACPI enabled systems by parsing MADT table or for older
> systems by parsing MP table. But for OF based x86 systems, it is
> assumed & hardcoded to legacy PIC mode. This is a bug for
> platforms which are OF based but do not use 8259 compliant legacy
> PIC interrupt controller. Such platforms can not even boot because
> of this bug/hardcoding.
> 
> Fix this bug by adding support for configuration of init time
> interrupt delivery mode for x86 OF based systems by introducing a
> new optional boolean property 'intel,virtual-wire-mode' for
> interrupt-controller node of local APIC. This property emulates
> IMCRP Bit 7 of MP feature info byte 2 of MP floating pointer
> structure [1].
> 
> Defaults to legacy PIC mode if absent. Configures it to virtual
> wire compatibility mode if present.

> [1] https://www.manualslib.com/manual/77733/Intel-Multiprocessor.html?page=40#manual

Link: ?

...

> +	if (of_property_read_bool(dn, "intel,virtual-wire-mode")) {

You need a separate patch to show this property being added (yes,
I have just commented on your patch 2).

> +		printk(KERN_NOTICE "Virtual Wire compatibility mode.\n");
> +		pic_mode = 0;
> +	} else {
> +		printk(KERN_NOTICE "IMCR and PIC compatibility mode.\n");
> +		pic_mode = 1;

Why not pr_notice()  in both cases?

> +	}

-- 
With Best Regards,
Andy Shevchenko