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Date:   Thu, 16 Sep 2021 12:29:41 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Mike Rapoport <rppt@kernel.org>
Cc:     Juergen Gross <jgross@suse.com>, Jan Beulich <jbeulich@suse.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= 
        <marmarek@invisiblethingslab.com>, xen-devel@lists.xenproject.org,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/setup: call early_reserve_memory() earlier
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On Thu, Sep 16, 2021 at 12:09:27PM +0300, Mike Rapoport wrote:
> I think the first sentence about reserving memory before memblock
> allocations are possible is important and I think we should keep it.

I expanded that comment this way:

        /*
         * Do some memory reservations *before* memory is added to memblock, so
         * memblock allocations won't overwrite it.
         *
         * After this point, everything still needed from the boot loader or
         * firmware or kernel text should be early reserved or marked not RAM in
         * e820. All other memory is free game.
         *
         * This call needs to happen before e820__memory_setup() which calls the
         * xen_memory_setup() on Xen dom0 which relies on the fact that those
         * early reservations have happened already.
         */

-- 
Regards/Gruss,
    Boris.

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