linux-kernel - Re: [PATCH 1/2][RFC] x86/boot/e820: Introduce e820_table_ori to represent the real original e820 layout

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Message-ID: <20170622094030.7ge2g2wsvpc6lx5r@gmail.com>
Date:   Thu, 22 Jun 2017 11:40:30 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Chen Yu <yu.c.chen@...el.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Len Brown <lenb@...nel.org>, Ying Huang <ying.huang@...el.com>
Subject: Re: [PATCH 1/2][RFC] x86/boot/e820: Introduce e820_table_ori to
 represent the real original e820 layout


* Chen Yu <yu.c.chen@...el.com> wrote:

> Currently we try to have e820_table_firmware to represent the
> original firmware memory layout passed to us by the bootloader,
> however it is not the case, the e820_table_firmware might still
> be modified by linux:
> 1. During bootup, the efi boot stub might allocate memory via
>    efi service for the PCI device information structure, then
>    later e820_reserve_setup_data() reserved these dynamically
>    allocated structures(AKA, setup_data) in e820_table_firmware
>    accordingly.
> 2. The kexec might also modify the e820_table_firmware.

Hm, so why does the EFI code modify e280_table_firmware - why doesn't
it modify e820_table?

I.e. what is the point of having 3 different versions of the
memory layout table?

Thanks,

	Ingo