Bug 154796 - Missing /dev/kmem, cannot read from kernel virtual memory.
Missing /dev/kmem, cannot read from kernel virtual memory.
Status: CLOSED NOTABUG
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel (Show other bugs)
4.0
x86_64 Linux
medium Severity medium
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Assigned To: Dave Jones
Brian Brock
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Depends On:
Blocks:
  Show dependency treegraph
 
Reported: 2005-04-14 04:35 EDT by Abhijit Toley
Modified: 2015-01-04 17:18 EST (History)
2 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2005-04-21 21:17:46 EDT
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RHEL 7.3 requirements from Atomic Host:


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Description Abhijit Toley 2005-04-14 04:35:07 EDT
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040510

Description of problem:

1)
We need to access kernel virtual memory and we do it through /dev/kmem.
But there is no /dev/kmem in the above mentioned kernel series. 

2)
We need /proc/kallsyms also, so that we can get the address (in the kernel
virtual memory) of a symbol from it and then go to that offset in /dev/kmem
to get the symbol.

In short, we need both /dev/kmem and /proc/kallsyms to be present.

Q1)
Do we need to follow certain steps for /dev/kmem to get created when the 
kernel boots?

Q2)
If either of these is not going to be provided by RedHat, then could you 
please suggest alternatives?

Thanks.

Version-Release number of selected component (if applicable):
2.6.9-5.EL, 2.6.9-6.26.ELsmp (amongst others of the same series)

How reproducible:
Always

Steps to Reproduce:
1. Install RHEL4 by an FTP installation. Just follow the steps as promted.
2. Find that /dev/kmem does not exist.

  

Additional info:
Comment 1 Abhijit Toley 2005-04-14 04:38:11 EDT
This is an issue on i686 as well as x86_64. 
Comment 2 Dave Jones 2005-04-21 21:17:46 EDT
Q1.
/dev/kmem support was intentionally removed, as it served no practical purpose
other than to serve as a potential security problem (by allowing root users to
modify kernel memory), or to enable binary module drivers to access
structures/functions they shouldn't be touching.

Q2.
Only use exported functions.

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