On Wed, Nov 07, 2001 at 10:18:25AM +0800, wctan@netwxs.com.my wrote: > I am Linux Internals by Moshe Bar. > on page 83, I come across this: > > "Unlike other UNIX implementations, however, please note that > this process structure does not occupy space in real sense of > world. How is this possible? > > Since the advent of Linux kernel 2.2.x, the task_struct is > allocated at the bottom of the kernel stack. It is therefore > possible to overlap the task_struct on the kernel stack because > the kernel_stack is a per-task structure exactly as the > task_struct is...bla bla bla... > > Basically, what the kernel does is decrease the size of the > "usable" kernel stack to around 7,323 bytes, by allocating the > task structure in the bottom of the stack" > > What does all these means? > What is kernel_struct cause I can't grep it anywhere? There is no such thing as kernel_struct in linux-2.4. > And precisely what is the kernel stack like? A stack, just like any other stack. > Also, isn't there multiple task_struct, how can the kernel just > put in the bottom of stack, won't it overflow and overwrite the > kernel data? The kernel maintains a separate kernel stack for each task. Erik -- J.A.K. (Erik) Mouw, Information and Communication Theory Group, Faculty of Information Technology and Systems, Delft University of Technology, PO BOX 5031, 2600 GA Delft, The Netherlands Phone: +31-15-2783635 Fax: +31-15-2781843 Email: J.A.K.Mouw@its.tudelft.nl WWW: http://www-ict.its.tudelft.nl/~erik/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ IRC Channel: irc.openprojects.net / #kernelnewbies Web Page: http://www.kernelnewbies.org/
