Advertisement

05.06.2008 at 11:05PM PDT, ID: 23381761
[x]
Attachment Details
[x]
The Solution Rating System

With so many solutions, how can you tell which solutions are most likely to help you and which ones are not? To provide you with a tool to use, we rate our solutions based on various elements that most accurately determine if a solution is a quality solution. To explain what factors affect the solution rating, here are the elements we take into consideration when formulating our solution rating.

  • The Grade of the Solution
  • The Zone Rank of the Expert Providing the Solution
  • The Number of Author and Expert Comments
  • The Number of Experts Contributing
  • The Feedback of the Community

Your Input Matters
Because of the way the system is set up, the most important variable in this equation is you. As a member of Experts Exchange, you are able to cast your vote on the quality of the solutions in regard to how complete, accurate, helpful and easy to understand each solution is. When you provide your feedback, each rating is adjusted accordingly. So, if you see a solution that has a poor rating that you think is a good solution, let us know by rating it. As you do, the rating will be adjusted and will become more accurate for other members of our site.

If you have any suggestions that you would like to make for our rating system, please ask a question in the Suggestions Zone of Community Support.

Thank you!

How Linux kernel differentiate between virtual address space for kernel and virtual address space for user process

Tags: linux, linux kernel, 2.6.18, Linux memory management
I am trying to understand how Linux kernel differentiates between virtual address space of kernel and virtual address space of user space process for Intel CPU architecture .
Linux KERNEL loads at PAGE_OFFSET 0xc0000000 which is start of virtual address space for kernel, while User space process uses virtual address less then 0xc0000000 (0-3GB).
Physical memory RAM address mapped to 0x0 to kernel virtual address space 0xc0000000 (LOW_MEM 0-896 MB)
So my questions:

1.      Where are page tables for kernel virtual address space and page table for user process virtual  
address space? When page tables for kernel and process virtual address space get  loaded in CPU?

2.      How both virtual address spaces are  handled in Linux   ?

3.      What happen at the time of system call from user space process to kernel in terms of this both virtual address space?
Start your free trial to view this solution
Question Stats
Zone: Programming
Question Asked By: hirakpatel
Solution Provided By: ravenpl
Participating Experts: 1
Solution Grade: B
Views: 45
Translate:
Loading Advertisement...
05.07.2008 at 01:05PM PDT, ID: 21519901

Rank: Guru

All comments and solutions are available to Premium Service Members only.

Start your 7-day free trial and see for yourself why Experts Exchange is the easiest and most proven technology resource in the world. Get Started

Already a member? Login to view this solution.

 
05.11.2008 at 07:13AM PDT, ID: 21542491

All comments and solutions are available to Premium Service Members only.

Start your 7-day free trial and see for yourself why Experts Exchange is the easiest and most proven technology resource in the world. Get Started

Already a member? Login to view this solution.

 
05.11.2008 at 09:25AM PDT, ID: 21542810

Rank: Guru

All comments and solutions are available to Premium Service Members only.

Start your 7-day free trial and see for yourself why Experts Exchange is the easiest and most proven technology resource in the world. Get Started

Already a member? Login to view this solution.

 
 
Loading Advertisement...
Microsoft
  • Internet Protocols
  • Applications
  • Development
  • OS
  • Hardware
  • Windows Security
Apple
  • Operating Systems
  • Hardware
  • Programming
  • Networking
  • Software
Internet
  • Search Engines
  • File Sharing
  • WebTrends / Stats
  • Spy / Ad Blockers
  • Web Browsers
  • New Net Users
  • Web Development
  • Chat / IM
  • Anti Spam
  • Web Servers
  • Anti-Virus
  • Email Clients
Gamers
  • Tips
  • Online / MMORPG
  • Puzzle
  • Emulators
  • Action / Adventure
  • Role Playing
  • Consoles
  • Game Programming
  • Strategy
  • Sports
  • Misc
  • Computer Games
Digital Living
  • Hardware
  • Automotive
  • New Net Users
  • New Users
  • Software
  • Digital Music
  • Gaming World
  • Home Security
  • Apple
  • Networking Hardware
Virus & Spyware
  • Vulnerabilities
  • IDS
  • Encryption
  • Anti-Virus
  • Operating Systems Security
  • Software Firewalls
  • WebApplications
  • Cell Phones
  • Operating Systems
  • Internet
  • Hardware Firewalls
Hardware
  • Displays / Monitors
  • Handhelds / PDAs
  • Components
  • Peripherals
  • Laptops/Notebooks
  • Servers
  • Misc
  • Apple
  • Embedded Hardware
  • Networking Hardware
  • Storage
  • Desktops
  • New Users
Software
  • System Utilities
  • Industry Specific
  • Network Management
  • Photos / Graphics
  • Page Layout
  • VMware
  • Misc
  • Web Development
  • OS
  • CYGWIN
  • Voice Recognition
  • Virtualization
  • Message Queue
  • Quality Assurance
  • Security
  • Firewalls
  • MultiMedia Applications
  • Development
  • Database
  • Office / Productivity
  • Business Management
  • OS/2 Apps
  • Server Software
  • Internet / Email
ITPro
  • OS
  • Storage
  • Encryption
  • Operating Systems Security
  • Apple Hardware
  • Laptops & Notebooks
  • Servers
  • Networking Hardware
  • Peripherals
  • Devices
  • Displays / Monitors
  • WebTrends / Stats
  • Search Engines
  • Firewalls
  • Web Computing
  • WebApplications
  • IDS
  • Vulnerabilities
  • Email Clients
  • File Sharing
  • Spy / Ad Blockers
  • Web Browsers
  • Web Servers
  • Networking
  • Anti-Virus
  • Consulting
  • Chat / IM
  • Anti Spam
Developer
  • Web Servers
  • Web Browsers
  • Game Programming
  • Dev Tools
  • Industry Specific
  • Office / Productivity
  • Database
  • CYGWIN
  • Web Development
  • Search Engines
  • File Sharing
  • WebTrends / Stats
  • Programming
  • Content Management
  • Application Servers
  • Protocols
Storage
  • Removable Backup Media
  • Storage Technology
  • Servers
  • Grid
  • Remote Access
  • Backup / Restore
  • Misc
  • Hard Drives
OS
  • Miscellaneous
  • Security
  • Development
  • Linux
  • VMware
  • MainFrame OS
  • Unix
  • Apple
  • OS / 2
  • AS / 400
  • BeOS
  • Microsoft
  • VMS / OpenVMS
Database
  • Oracle
  • Miscellaneous
  • MySQL
  • Software
  • Sybase
  • Contact Management
  • PostgreSQL
  • Data Manipulation
  • Clarion
  • InterSystems Cache
  • Siebel
  • MUMPS
  • OLAP
  • SQLBase
  • SAS
  • GIS & GPS
  • 4GL
  • Berkeley DB
  • DB2
  • Informix
  • Interbase / Firebird
  • FoxPro
  • Reporting
  • LDAP
  • Filemaker Pro
  • MS SQL Server
  • dBase
  • MS Access
Security
  • Misc
  • Web Browsers
  • Software Firewalls
  • Operating Systems Security
  • File Sharing
  • Spy / Ad Blockers
  • Vulnerabilities
  • WebApplications
  • IDS
  • Anti-Virus
  • Encryption
  • Anti Spam
  • Email Clients
  • VPN
  • Chat / IM
Programming
  • Editors IDEs
  • Installation
  • Handhelds / PDAs
  • Multimedia Programming
  • System / Kernel
  • Automation
  • Algorithms
  • Game
  • Signal Processing
  • Project Management
  • Open Source
  • Database
  • Misc
  • Languages
  • Processor Platforms
  • Theory
Web Development
  • Scripting
  • Blogs
  • Web Servers
  • Software
  • Search Engines
  • Web Graphics
  • Web Services
  • Images
  • Internet Marketing
  • Images and Photos
  • Components
  • Document Imaging
  • Web Languages/Standards
  • Illustration
  • WebApplications
  • Fonts
  • WebTrends / Stats
  • Authoring
  • Digital Camera Software
  • Miscellaneous
Networking
  • Protocols
  • Apple Networking
  • Network Management
  • Message Queue
  • Application Servers
  • Content Management
  • File Servers
  • Email Servers
  • Misc
  • Java Editors & IDEs
  • Wireless
  • Networking Hardware
  • Backup / Restore
  • System Utilities
  • ISPs & Hosting
  • Web Servers
  • Storage Technology
  • Removable Backup Media
  • Servers
  • Web Computing
  • Broadband
  • Grid
  • OS / 2
  • Novell Netware
  • Unix Networking
  • Windows Networking
  • Security
  • Telecommunications
  • Operating Systems
  • Linux Networking
Other
  • Lounge
  • Business Travel
  • Community Support
  • New Net Users
  • Philosophy / Religion
  • Math / Science
  • Miscellaneous
  • URLs
  • Expert Lounge
  • Politics
  • Puzzles / Riddles
  • Automotive
Community Support
  • Suggestions
  • New to EE
  • New Topics
  • CleanUp
  • Announcements
  • General
  • Feedback
  • Input
  • EE Bugs
 
05.07.2008 at 01:05PM PDT, ID: 21519901

Rank: Guru

1. the current table is loaded into cr3 http://en.wikipedia.org/wiki/Control_Registers
    it's changed at sysexit function(the function returns to some task, and every task has it's own mapping table)
2. Just like You described, <3G are user pages, >3G are kernel pages
    While cpu is in non-priviledged mode(user) it uses local descriptor table only(where segments are defined upto 3G only)
    While cpu is in priviledged mode(kernel) it's allowed to use uses global descriptor table(where 3-4G segments are available)
3. The cpu enters privileged mode,a nd therefore GDT is available.
Accepted Solution
 
05.11.2008 at 07:13AM PDT, ID: 21542491
SO I want to clarify one thing that Linux works following way :
1.First selects the segment and then inside segmented  linear address space ,Linux will access page table to covert virtual address sapce to get physical page and offset locaton in page table.
2.It means linux has following  segments:
 1) Linux Process code segment
  2)Linux Process data segment
 Above two segments per process basis  and following two common for all process:
 3)Linux kernel code segment
 4)Linux kernel data segment
But I am confused about that how can process have different kernel stack when it enter throgh system call in kernel space ?
 
05.11.2008 at 09:25AM PDT, ID: 21542810

Rank: Guru

 
 
20080236-EE-VQP-29 / EE_QW_2_20070628