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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Hou Wenlong <houwenlong.hwl@antgroup.com>,
        linux-kernel@vger.kernel.org
Cc:     Lai Jiangshan <jiangshan.ljs@antgroup.com>,
        Hou Wenlong <houwenlong.hwl@antgroup.com>,
        Alexey Makhalov <amakhalov@vmware.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Borislav Petkov <bp@alien8.de>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Brian Gerst <brgerst@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        David Woodhouse <dwmw@amazon.co.uk>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Juergen Gross <jgross@suse.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        "Mike Rapoport (IBM)" <rppt@kernel.org>,
        Pasha Tatashin <pasha.tatashin@soleen.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "Srivatsa S. Bhat (VMware)" <srivatsa@csail.mit.edu>,
        Suren Baghdasaryan <surenb@google.com>,
        Usama Arif <usama.arif@bytedance.com>,
        virtualization@lists.linux-foundation.org,
        VMware PV-Drivers Reviewers <pv-drivers@vmware.com>,
        x86@kernel.org, xen-devel@lists.xenproject.org
Subject: Re: [PATCH RFC 0/4] x86/fixmap: Unify FIXADDR_TOP
In-Reply-To: <cover.1684137557.git.houwenlong.hwl@antgroup.com>
References: <cover.1684137557.git.houwenlong.hwl@antgroup.com>
Date:   Wed, 07 Jun 2023 20:29:32 +0200
Message-ID: <877csfjfcj.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Mon, May 15 2023 at 16:19, Hou Wenlong wrote:

> This patchset unifies FIXADDR_TOP as a variable for x86, allowing the
> fixmap area to be movable and relocated with the kernel image in the
> x86/PIE patchset [0]. This enables the kernel image to be relocated in
> the top 512G of the address space.

What for? What's the use case.

Please provide a proper argument why this is generally useful and
important.

Thanks,

        tglx