Hi all, I went through the code of do_fork. do_fork calls copy_process which in turn calls dup_task_struct .Here alloc_thread_info allocates the kernel stack for the process Thanks all Regards Suthambhara On Wed, 13 Oct 2004 08:59:14 +0530, suthambhara nagaraj <suthambhara@xxxxxxxxx> wrote: > Thanks Neil. I was an idiot to have overlooked that. > Thanks once again > > Regards > Suthambhara > > > > > On Tue, 12 Oct 2004 07:09:09 -0400, Neil Horman <nhorman@xxxxxxxxxx> wrote: > > > > > > suthambhara nagaraj wrote: > > > Hi all, > > > > > > I have not understood how the common kernel stack in the > > > init_thread_union(2.6 ,init_task_union in case of 2.4) works for all > > > the processes which run on the same processor. The scheduling is round > > > robin and yet the things on the stack (saved during SAVE_ALL) have to > > > be maintained after a switch without them getting erased. I am > > > familiar with only the i386 arch implementation. > > > > > > Please help > > > > > There is no such thing as "the common kernel stack". Each process > > (represented by a task_struct in the kernel) has its own private data > > space to be used as a kernel stack when that process traps into the > > kernel. You can see where this per task_struct stack space is reserved > > in the definition of task_union. init_[task|thread]_union just defines > > the first task union in the system. Because of the way unions are laid > > out in memory, The kernel knows that when a process traps into kernel > > space, it just needs to round the current task pointer to the nearest 8k > > (prehaps 4k in 2.6) boundary, and thats the start of that processes > > kernel stack. Thats how the SAVE_ALL command avoids trampling registers. > > > > HTH > > Neil > > > regards, > > > Suthambhara > > > - > > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > Please read the FAQ at http://www.tux.org/lkml/ > > > > -- > > /*************************************************** > > *Neil Horman > > *Software Engineer > > *Red Hat, Inc. > > *nhorman@xxxxxxxxxx > > *gpg keyid: 1024D / 0x92A74FA1 > > *http://pgp.mit.edu > > ***************************************************/ > > > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
