linux-kernel - Re: [PATCH v3 1/3] x86/64: Make kernel text mapping always take one whole page table in early boot code

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Message-ID: <E0D4D4C8-F4BE-437B-B1A4-EE033074FAE7@suse.de>
Date:   Wed, 04 Jan 2017 15:00:59 +0200
From:   Boris Petkov <bp@...e.de>
To:     Baoquan He <bhe@...hat.com>, tglx@...utronix.de, hpa@...or.com,
        mingo@...hat.com
CC:     linux-kernel@...r.kernel.org, x86@...nel.org,
        keescook@...omium.org, yinghai@...nel.org, thgarnie@...gle.com,
        kuleshovmail@...il.com, luto@...nel.org, mcgrof@...nel.org,
        anderson@...hat.com, dyoung@...hat.com
Subject: Re: [PATCH v3 1/3] x86/64: Make kernel text mapping always take one whole page table in early boot code

On January 4, 2017 10:37:31 AM GMT+02:00, Baoquan He <bhe@...hat.com> wrote:
>In early boot code level2_kernel_pgt is used to map kernel text. And
>its
>size varies with KERNEL_IMAGE_SIZE and fixed at compiling time. In fact
>we can make it always take 512 entries of one whole page table, because
>later function cleanup_highmap will clean up the unused entries. With
>the
>help of this change kernel text mapping size can be decided at runtime
>later, 512M if kaslr is disabled, 1G if kaslr is enabled.
Question: so why are we even having that distinction? Why aren't we making text mapping size 1G by default and be done with it?
-- 
Sent from a small device: formatting sux and brevity is inevitable.