[bug #61148] cutmem not wokring on old machines

[Alexey Kuznetsov]

Follow-up Comment #4, bug #61148 (project grub):

GRUB_TERMINAL=console

makes gurb2 works fast!

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[bug #61148] cutmem not wokring on old machines

[Alexey Kuznetsov]

Follow-up Comment #3, bug #61148 (project grub):

My guess was limit memory map returned by e820 by size of 20M manually. So, I
did patch grub source code with following:


diff --git a/grub-core/kern/i386/pc/mmap.old b/grub-core/kern/i386/pc/mmap.c
index c0c3c35..0eb76d9 100644
--- a/grub-core/kern/i386/pc/mmap.old
+++ b/grub-core/kern/i386/pc/mmap.c
@@ -134,6 +134,10 @@ grub_get_mmap_entry (struct grub_machine_mmap_entry
*entry,
   else
 entry->size = regs.ecx;
 
+  if (entry->addr == 0x0010) {
+entry->len -= 0x134;
+  }
+
   /* return the continuation value */
   return regs.ebx;
 }



But that did not succeed. Grub still works slowly. Does anyone know why kernel
with 'mem=2020M' argument works fast, and same memory map does not fix grub
'slow down' issue?

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[bug #61148] cutmem not wokring on old machines

[Alexey Kuznetsov]

Follow-up Comment #2, bug #61148 (project grub):

I forget to mention 'grub-legacy' works fine, not slowdowns!

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[bug #61148] cutmem not wokring on old machines

[Alexey Kuznetsov]

Follow-up Comment #1, bug #61148 (project grub):

fast logs:

https://linux-hardware.org/?probe=59b41381ed

slow logs:

https://linux-hardware.org/?probe=28a5b48a05

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[bug #61148] cutmem not wokring on old machines

[Alexey Kuznetsov]

URL:
  

 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:

[0.00] BIOS-provided physical RAM map:
[0.00] BIOS-e820: [mem 0x-0x0009fbff] usable
[0.00] BIOS-e820: [mem 0x0009fc00-0x0009]
reserved
[0.00] BIOS-e820: [mem 0x000e-0x000f]
reserved
[0.00] BIOS-e820: [mem 0x0010-0x7f73] usable
[0.00] BIOS-e820: [mem 0x7f74-0x7f74] ACPI
data
[0.00] BIOS-e820: [mem 0x7f75-0x7f7f] ACPI
NVS
[0.00] e820: remove [mem 0x7e40-0xfffe] usable
[0.00] Notice: NX (Execute Disable) protection missing in CPU!
[0.00] user-defined physical RAM map:
[0.00] user: [mem 0x-0x0009fbff] usable
[0.00] user: [mem 0x0009fc00-0x0009] reserved
[0.00] user: [mem 0x000e-0x000f] reserved
[0.00] user: [mem 0x0010-0x7e3f] usable
[0.00] user: [mem 0x7f74-0x7f74] ACPI data
[0.00] user: [mem 0x7f75-0x7f7f] 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 0x7e4 0x7f74'

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...@12.20.38.jpg  Size:
1MiB   By: axet



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