linux-kernel - Re: [PATCH v2 0/2] Make it possible to reserve memory on 64bit platform

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Message-ID: <15269a61-3b16-4c07-2486-6940c559261e@redhat.com>
Date:   Mon, 18 Jan 2021 10:50:26 +0100
From:   David Hildenbrand <david@...hat.com>
To:     "zhaowei1102@...ndersoft.com" <zhaowei1102@...ndersoft.com>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        kerneldev <kerneldev@...smulder.nl>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Joe Perches <joe@...ches.com>,
        gpiccoli <gpiccoli@...onical.com>, aquini <aquini@...hat.com>,
        gustavoars <gustavoars@...nel.org>, ojeda <ojeda@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        guohanjun <guohanjun@...wei.com>,
        mchehab+huawei <mchehab+huawei@...nel.org>
Subject: Re: [PATCH v2 0/2] Make it possible to reserve memory on 64bit
 platform

On 18.01.21 04:51, zhaowei1102@...ndersoft.com wrote:
>     On Sat, Jan 16, 2021 at 2:43 AM Wesley Zhao
>     <zhaowei1102@...ndersoft.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.
>     Sorry，what is your point：
>      static int __init reserve_setup(char *str)
>      static struct resource reserve[MAXRESERVE];
>      for (;;) {
>      unsigned int io_start, io_num;*  // these code is not compatible
>     with 64bit，i start from here*
> 

Dan's point is that you should look into using "memmap=" instead of
"reserve=".

-- 
Thanks,

David / dhildenb