hi jon,
the module is compiling & loading fine now!
I had loaded the incorrect kernel ver. (different from the one in
the kernel source tree) and the reason all those RISC reg. showing
up was that i had run an unsuccessfull build for the ARM arch. in
this source tree, so i guess some old files were conflicting!!
thanks all,
-mandeep
On Mon, 2005-01-03 at 15:36, Mandeep Sandhu wrote:
> hi jon,
>
> I was trying out your module.
>
> i have a makefile in my working dir which has just one line
>
> obj-m := threadinfo_test.o
>
> i compile the module with the following command
>
> $ make -C /usr/src/linux-2.6.9 M=$PWD modules
> make: Entering directory `/usr/src/linux-2.6.9'
> CC [M] /home/msandhu/test/threadinfo_test.o
> include/linux/time.h: In function `jiffies_to_timespec':
> include/linux/time.h:257: invalid register name `r4' for register variable
> include/linux/time.h:257: invalid register name `r0' for register variable
> include/linux/time.h:257: invalid register name `r2' for register variable
> include/linux/time.h:257: invalid register name `r1' for register variable
> include/linux/time.h:257: unknown register name `lr' in `asm'
> include/linux/time.h:257: unknown register name `ip' in `asm'
> include/linux/time.h: In function `jiffies_to_timeval':
> include/linux/time.h:295: invalid register name `r4' for register variable
> include/linux/time.h:295: invalid register name `r0' for register variable
> include/linux/time.h:295: invalid register name `r2' for register variable
> include/linux/time.h:295: invalid register name `r1' for register variable
> include/linux/time.h:295: unknown register name `lr' in `asm'
> include/linux/time.h:295: unknown register name `ip' in `asm'
> include/asm/semaphore.h: In function `down':
> include/asm/semaphore.h:77: unknown register name `lr' in `asm'
> include/asm/semaphore.h:77: unknown register name `ip' in `asm'
> include/asm/semaphore.h: In function `down_interruptible':
> include/asm/semaphore.h:87: unknown register name `lr' in `asm'
> include/asm/semaphore.h:87: unknown register name `ip' in `asm'
> include/asm/semaphore.h: In function `down_trylock':
> include/asm/semaphore.h:92: unknown register name `lr' in `asm'
> include/asm/semaphore.h:92: unknown register name `ip' in `asm'
> include/asm/semaphore.h: In function `up':
> include/asm/semaphore.h:103: unknown register name `lr' in `asm'
> include/asm/semaphore.h:103: unknown register name `ip' in `asm'
> make[1]: *** [/home/msandhu/test/threadinfo_test.o] Error 1
> make: *** [_module_/home/msandhu/test] Error 2
> make: Leaving directory `/usr/src/linux-2.6.9'
>
>
> my running kernel is a 2.6.4 and the source i'm using is that of 2.6.9
> (that should'nt cause any problems right....?)
>
> Why is it picking up all those RISC registers....!! :(
>
> Thanks and a happy new year to you.
>
> -mandeep
>
>
> On Mon, 2005-01-03 at 09:03, Jon Masters wrote:
> > On Thu, 30 Dec 2004 12:03:24 +0530, Mandeep Sandhu
> > <Mandeep_Sandhu@xxxxxxxxxxx> wrote:
> >
> > > I was going through RML's book (ch. 2). There he mentions that
> > > having the new structure "thread_info" helps in calculating the
> > > offsets using assembly code rather easily. How does having a struct
> > > (which has a pointer to task_struct) stored on the top a process
> > > kernel stack be more advantageous than storing a pointer to
> > > task_struct itself on the same location!?
> >
> > He's referring to the fact that thread_info contains a few very useful
> > elements that we might want to access quickly - for other stuf we need
> > to resort to the task_struct itself. As rml also notes, the current
> > task is often available for indirection access via a specific register
> > when in kernel mode - r2 on PowerPC (sorry rml, for once thinking that
> > was incorrect).
> >
> > > Furthermore the assembly code used to get a pointer to thread_info
> > > masks the lower 13 bits to obtain the pointer.
> >
> > It masks out the kernel mode stack to get at the thread_info at the bottom.
> >
> > > I was trying to
> > > do a "sizeof" of struct thread_info from a sample prog. but was
> > > getting errors when i tried to include linux/thread_info.h.....so
> > > i thought i'll ask here! :)
> >
> > Don't include that directly in userspace, copy the struct define and
> > use that if needed. Perhaps also just write a very simple LKM to do it
> > for you:
> >
> > /*
> > * threadinfo_test.c - A simple test LKM.
> > *
> > */
> >
> > #include <linux/module.h> /* module macros */
> > #include <linux/init.h> /* init macros */
> >
> > #include <linux/config.h>
> > #include <linux/errno.h>
> > #include <linux/kernel.h>
> >
> > int __init threadinfo_init(void)
> > {
> >
> > printk("The size of thread_info is %d bytes.\n",
> > sizeof(struct thread_info));
> >
> > return 0;
> > }
> >
> > void __exit threadinfo_exit(void)
> > {
> > }
> >
> > module_init(threadinfo_init);
> > module_exit(threadinfo_exit);
> >
> > MODULE_AUTHOR("Jon Masters <jcm@xxxxxxxxxxxxxx>");
> > MODULE_LICENSE("GPL");
> >
> > Cheers,
> >
> > Jon.
>
> --
> Kernelnewbies: Help each other learn about the Linux kernel.
> Archive: http://mail.nl.linux.org/kernelnewbies/
> FAQ: http://kernelnewbies.org/faq/
>
--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
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