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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Sun, 17 Jan 2021 11:02:28 -0800
Message-ID: <CAPcyv4hGu3r=m+7Wkf3a94G=ZM4cQB87pt0ThadoUrk8cY7ovw@mail.gmail.com>
Subject: Re: [PATCH v2 0/2] Make it possible to reserve memory on 64bit platform
To:     Wesley Zhao <zhaowei1102@thundersoft.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Kees Cook <keescook@chromium.org>,
        Thomas Gleixner <tglx@linutronix.de>, kerneldev@karsmulder.nl,
        Arvind Sankar <nivedita@alum.mit.edu>,
        Joe Perches <joe@perches.com>, gpiccoli@canonical.com,
        aquini@redhat.com, gustavoars@kernel.org, ojeda@kernel.org,
        ndesaulniers@gooogle.com,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        David Hildenbrand <david@redhat.com>, guohanjun@huawei.com,
        mchehab+huawei@kernel.org
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On Sat, Jan 16, 2021 at 2:43 AM Wesley Zhao <zhaowei1102@thundersoft.com> wrote:
>
> I was trying to reserve some memory to save logs incase that Android panic or hang and then
> I can read the logs from QNX side from the memory reserved before on the Qualcomm 8155 hypervisor platform,
> and I find the "reserve=" parameter only support 32bit,so I made some change and send these patches.

See Documentation/admin-guide/kernel-parameters.txt

        memmap=nn[KMG]$ss[KMG]
                        [KNL,ACPI] Mark specific memory as reserved.
                        Region of memory to be reserved is from ss to ss+nn.
                        Example: Exclude memory from 0x18690000-0x1869ffff
                                 memmap=64K$0x18690000
                                 or
                                 memmap=0x10000$0x18690000
                        Some bootloaders may need an escape character
before '$',
                        like Grub2, otherwise '$' and the following number
                        will be eaten.