linux-kernel - Re: [PATCH] x86/mce: Increase maximum number of banks to 64

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Message-ID: <20200820171518.GB17271@zn.tnic>
Date:   Thu, 20 Aug 2020 19:15:18 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <Yazen.Ghannam@....com>
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        tony.luck@...el.com, x86@...nel.org,
        Smita.KoralahalliChannabasappa@....com
Subject: Re: [PATCH] x86/mce: Increase maximum number of banks to 64

On Thu, Aug 20, 2020 at 05:06:24PM +0000, Yazen Ghannam wrote:
> From: Akshay Gupta <Akshay.Gupta@....com>
> 
> ...because future AMD systems will support up to 64 MCA banks per CPU.
> 
> MAX_NR_BANKS is used to allocate a number of data structures, and it is
> used as a ceiling for values read from MCG_CAP[Count]. Therefore, this
> change will have no functional effect on existing systems with 32 or
> fewer MCA banks per CPU.

Of course it will, grep for MAX_NR_BANKS and look at all those bitmaps
and arrays which get defined with MAX_NR_BANKS size. With your change,
they will double in size.

How much does vmlinux size grow with your change?

-- 
Regards/Gruss,
    Boris.

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