linux-kernel - Re: [PATCH] x86: add support DM&P devices

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Date:   Wed, 13 Oct 2021 18:57:49 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Marcos Del Sol Vives <marcos@...a.pet>
Cc:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: add support DM&P devices

On Fri, Oct 08, 2021 at 06:22:46PM +0200, Marcos Del Sol Vives wrote:
> +config CPU_SUP_DMP_32
> +	default y
> +	bool "Support DM&P processors" if PROCESSOR_SELECT
> +	depends on !64BIT

You mean

	depends on X86_32

?

Wikipedia says those things are 32-bit.

> +	help
> +	  This enables detection, tunings and quirks for DM&P processors
> +
> +	  You need this enabled if you want your kernel to run on a
> +	  DM&P CPU. Disabling this option on other types of CPUs

So I'm not sure about the nomenclature: those CPUs are called Vortex86
and DM&P is simply the next owner of the IP:

"Vortex86 previously belonged to SiS, which got the basic design from
Rise Technology.[1] SiS sold it to DM&P Electronics[2] in Taiwan."

So I'm thinking we should call everything Vortex, the file vortex.c, the
vendor define X86_VENDOR_VORTEX and so on.

> +	  makes the kernel a tiny bit smaller. Disabling it on a DM&P
> +	  CPU might render the kernel unbootable.

Why unbootable? It looks like those are perfect clones: "No special init
required for DM&P processors." it says in the patch. :)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette