[bug #61148] cutmem not wokring on old machines

[Alexey Kuznetsov]

URL:
  <https://savannah.gnu.org/bugs/?61148>

                 Summary: cutmem not wokring on old machines
                 Project: GNU GRUB
            Submitted by: axet
            Submitted on: Sun 12 Sep 2021 09:34:02 AM UTC
                Category: None
                Severity: Major
                Priority: 5 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 
                 Release: 2.00
         Discussion Lock: Any
         Reproducibility: None
         Planned Release: None

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Details:

Hello!

My old notebook has memory issues and requires to cut memory region to work
propertly.

>From kernel perspective it looks like this:

[    0.000000] BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
[    0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff]
reserved
[    0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff]
reserved
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000007f73ffff] usable
[    0.000000] BIOS-e820: [mem 0x000000007f740000-0x000000007f74ffff] ACPI
data
[    0.000000] BIOS-e820: [mem 0x000000007f750000-0x000000007f7fffff] ACPI
NVS
[    0.000000] e820: remove [mem 0x7e400000-0xfffffffffffffffe] usable
[    0.000000] Notice: NX (Execute Disable) protection missing in CPU!
[    0.000000] user-defined physical RAM map:
[    0.000000] user: [mem 0x0000000000000000-0x000000000009fbff] usable
[    0.000000] user: [mem 0x000000000009fc00-0x000000000009ffff] reserved
[    0.000000] user: [mem 0x00000000000e0000-0x00000000000fffff] reserved
[    0.000000] user: [mem 0x0000000000100000-0x000000007e3fffff] usable
[    0.000000] user: [mem 0x000000007f740000-0x000000007f74ffff] ACPI data
[    0.000000] user: [mem 0x000000007f750000-0x000000007f7fffff] ACPI NVS

If this region is not removed my notebook works SUPER slow and every click
takes few seconds to process. Same affects grub2. If region in use grub2 takes
2 minutes to boot into kernel. I recorded youtube video:

https://youtu.be/BlTii6QL5oY

I know grub2 has a 'cutmem' command which is not working propertly. When I
issue a:

'cutmem 0x7e40000 0x7f74ffff'

grub2 reports no changes is 'lsmmap' which is not correct. I tested 'cutmem'
on my second notebook with efi loader, and cutmem affects 'lsmmap' output.

Here a few screenshots of grub2 boot process attached.



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File Attachments:


-------------------------------------------------------
Date: Sun 12 Sep 2021 09:34:02 AM UTC  Name: 2021-09-12@12.20.38.jpg  Size:
1MiB   By: axet

<http://savannah.gnu.org/bugs/download.php?file_id=51896>

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