Bug 784569 - mem kernel parameter sets wrong memory size
Summary: mem kernel parameter sets wrong memory size
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel
Version: 5.8
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: rc
: ---
Assignee: Red Hat Kernel Manager
QA Contact: Red Hat Kernel QE team
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2012-01-25 12:02 UTC by Adam Okuliar
Modified: 2013-02-15 12:59 UTC (History)
0 users

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2013-02-15 12:59:09 UTC
Target Upstream Version:

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Description Adam Okuliar 2012-01-25 12:02:57 UTC 
Description of problem:
mem kernel parameter sets wrong memory size

Version-Release number of selected component (if applicable):
2.6.18-305.el5

How reproducible:
100%

Steps to Reproduce:
1. grab machine from beaker with more than 4096M of memory
2. add mem=4096M to kernel parameters
3. reboot the system
  
Actual results:
free -m
             total       used       free     shared    buffers     cached
Mem:          1970        507       1463          0         32        276
-/+ buffers/cache:        198       1772
Swap:        13983          0      13983

After reboot there is only bit less than 2G available in userspace, although available memory size should be close to 4G. 

Expected results:
mem kernel parameter sets correct memory size

Additional info:
Discovered on ibm-x3650m3-02.lab.eng.brq.redhat.com
Comment 1 Jes Sorensen 2013-02-15 12:59:09 UTC 
mem= refers to the end address of the physical memory on the system, not the
amount of memory in the system. Hence with leaving space for the BIOS and PCI
devices, you will always see some memory go beyond the 4GB address when you
have 4GB installed.

This is not a bug
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