Device Drivers Compiling Applications Package Managers RPM

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Device DriversCompiling ApplicationsPackage
Managers (RPM)

• CPSC 665
• Spring 2003
• Gold Team
• Philip Mattingly
• Brett Willman
• Derek Horton
• Ben Collins

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Devices Under Linux

• All device handling within the Linux kernel
  happens through special files.
• /dev
• Use no hard disk space
• Logically, these files are links to the device
  driver

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Devices Under Linux

• When processes open these files, the kernel
  redirects all read and write requests to the
  appropriate driver.

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Device Types

• Two types of these special files
• Block mode devices
• Character mode devices
• Network Interfaces

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Device Types

• Block mode devices
• Structure the data they contain into blocks
• Disks, floppies, CD-ROMs

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Device Types

• Character mode devices
• Require the kernel to send or receive data from
  them one byte at a time.
• Terminals, modems, printers

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Device Types

• Network Interface
• Packet oriented.
• No associated /dev file.
• eth0, eth1

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Device Control

• Major part of the operating system is device
  control.
• Almost all operations are performed by code that
  is specific to a device.

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Device Drivers

• Software layer that lies between the applications
  and the actual device.
• Drivers can be either compiled into the kernel or
  they can be compiled as modules that are loaded
  into the kernel at runtime.

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Security

• If the kernel has security holes, then the entire
  system has holes.
• Kernel modules are just as powerful as a root
  shell. Therefore, only root can load modules.
• Driver writes must be careful to not introduce
  security bugs (buffer overflows) into the kernel.

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Security

• Kernels can be compile monolithically, thus
  requiring no modules.
• Later kernels (2.2 and 2.4) can be configured to
  disable the loading of modules after bootup.

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Resources

• Linux Device Drivers.
• Linux Internals.
• Running Linux, 2nd Edition.

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Tarballs

• Filename.tar.gz
• Tape Archive GZIP Compression
• Standard package distribution over UNIX platforms
• Source code with configuration scripts

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Basic Steps

• Extract files from tarball
• Configure installation
• Read ALL installation documentation
• Compile source code
• Install executables and libraries
• Clean source (optional)

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1. Extract Tarball

• Tar zxfv filename.tar.gz
• (z) uncompress GZIP
• (x) Extract files from tape archive
• (f) Specify file name
• (v) Verbose

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2. Configure Installation

• ./configure --help
• Lists options available for installation
• Determine your needs
• ./configure --with-options
• Options include additional module support,
  installation directory
• Creates Makefile for next steps
• Shell script
• Configuration typically determines dependencies
  and required include files

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3. Compile Source Code

• make
• Compiles source code according to rules specified
  in the Makefile
• Output object code resides where it was compiled

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4. Install

• make install
• Installs object code according to rules specified
  in Makefile
• Determines directories to copy libraries and
  executables

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5. Make Clean

• make clean
• Not as common, but useful
• Cleans object code created from Step 3
• Prevents recompiling unwanted code

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Post Installation

• Modify application level configuration scripts
• httpd.conf, ntp.conf, etc
• Verify correctness

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RPM

• R Package Manager
• A Package is a collection of files associated
  with an application.
• Binary
• Source
• Configuration Files
• Documentation
• Libraries

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RPM

• RPM databases installed packages.
• Maintaining a Databases allows for
• Queries
• Verification
• Version Control

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Useful RPM Commands

• Installing packages (Upgrade)
• rpm Uhv package-name.i386.rpm
• Removing packages
• rpm e package-name
• Querying existence of packages
• rpm qa grep query

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Useful Query Commands

• Querying individual packages
• rpm qpi package-name
• File listing of individual packages
• rpm -qpl package-name

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Source RPMS

• All the files in the package besides the binaries
• Architecture independent
• Compiled during installation

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Tarball Vs RPM

• RPMs created from tarball and released afterwards
• RPMs configured for specific platform and
  architecture
• Tarballs can be configured to meet users needs
• Tarballs Optimize system resources