kallsyms_lookup_name
Hi, I need to use some unexported kernel symbols in my kernel module but in the particular kernel version i am based on (2.6.18 - RHEL 5.7), kallsyms_lookup_name is not exported and there is no kallsyms_on_each_symbol in this kernel. And I can't change the kernel owing to reasons i have no control over. In this scenario, how do i use unexported symbols. Is there any other mechanism by which i can lookup the address of a kernel symbol. Thanks. Venkatram ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Debugging the linux kernel core dump
On Fri, Aug 5, 2011 at 9:23 PM, Mulyadi Santosa wrote: > Hi... > > On Fri, Aug 5, 2011 at 12:23, Akash wrote: > > I think it was not built with -g otherwise the symbols would have been > there > > in the vmlinux itself, right ? > > That is the reason I need to add symbols externally. > > Please dont ask me to rebuild the kernel, this is vanilla OpenSUSE 11.3 > > symbols and debug kernel should be available somewhere. I just need to > know > > how/where to add the symbols. The problem is not reproducible, I need to > > debug the core which I have on hand. > > try to check opensuse repo, see which one provide kinda "debuginfo" > package for your kernel (at least that's how Fedora/RHEL call it). > Usually it will be located under /boot with quite obvious name > (suffixed with "debug" or similar) or you could just try to use > vmlinux as the symbol file > > NB: make sure you use the very same debuginfo package with your > current kernel version. Any slight difference could yield very > different symbol addresses. > Thanks Malyudi. Thats sounds like a reasonable approach. I did try to search kernel-debug RPMs for my kernel could not find any. May be I should just keep looking. On that note, I wonder what is the difference between kernel-base, kernel-default, kernel-devel, and similar other RPMs. I guess some contain binaries, some contain unstripped binaries and some contain soruces/headers. But which is which ?? I hate distros for creating so many RPMs. They could have included ALL of this in one RPM and users would not have minded. ->Akash > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer and consultant > > blog: the-hydra.blogspot.com > training: mulyaditraining.blogspot.com > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: how to freeze the 2.6 kernel on SMP m/c
On Fri, Aug 5, 2011 at 17:24, san deep wrote:
> Hi,
>
> Could you please suggest how to freeze the 2.6 kernel(SMP m/c) with
> my own dlkm with less number of code.
>
> I tried the below mentioned code snippet, it hangs only the terminal
> on which i executed the insmod command.
> Please correct the below code to freeze whole kernel.
>
> #include
> #include
> #include
> #include
>
> int init_module(void)
> {
> spinlock_t lock = SPIN_LOCK_UNLOCKED;
> while (1) {
> spin_lock(&lock);
> msleep(100);
> }
> //spin_unlock(lock);
> printk(KERN_INFO "Hello world :).\n");
> return 0;
> }
how about calling panic()?
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
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Re: Mapped more than Cached in /proc/meminfo
On Fri, Aug 5, 2011 at 21:16, =/_00/\/\ wrote: > Hi, > > I am trying to analyze memory usage on my system. > As first step I am monitoring /proc/meminfo. > Surprisingly I see Mapped value is more than Cached. > > So in which case is it possible to have Mapped more than Cached ? your apps mmap() less than the amount of files content that are cached through normal read() AFAIK -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Debugging the linux kernel core dump
Hi... On Fri, Aug 5, 2011 at 12:23, Akash wrote: > I think it was not built with -g otherwise the symbols would have been there > in the vmlinux itself, right ? > That is the reason I need to add symbols externally. > Please dont ask me to rebuild the kernel, this is vanilla OpenSUSE 11.3 > symbols and debug kernel should be available somewhere. I just need to know > how/where to add the symbols. The problem is not reproducible, I need to > debug the core which I have on hand. try to check opensuse repo, see which one provide kinda "debuginfo" package for your kernel (at least that's how Fedora/RHEL call it). Usually it will be located under /boot with quite obvious name (suffixed with "debug" or similar) or you could just try to use vmlinux as the symbol file NB: make sure you use the very same debuginfo package with your current kernel version. Any slight difference could yield very different symbol addresses. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: can i simply "re-version" the kernel down to 2.x?
On Fri, Aug 05, 2011 at 10:36:00AM -0400, Robert P. J. Day wrote:
>
> for reasons that don't need explaining, i need to rebuild my current
> 3.0.0... kernel so that it returns a "uname" version number of
> "2.whatever". i simply have an app i want to run that checks the
> output of "uname" and if it doesn't see a major number of "2", it goes
> a bit squirrelly.
If it is just one poorly written app you are trying to deal with, it
might just be easier to create a wrapper dll that traps the glibc uname
wrapper and hijacks the returned version. Something like this:
--- /dev/null 2011-08-02 20:23:03.358999850 -0500
+++ b/trapuname.c 2011-08-05 22:45:02.0 -0500
@@ -0,0 +1,43 @@
+/* trapuname: tool to fake uname release
+ * Copyright (C) 2011 Josh Cartwright
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
USA.
+ */
+#define _GNU_SOURCE
+#include
+#include
+#include
+#include
+#include
+
+int uname(struct utsname *u)
+{
+ const char *err;
+ int ret;
+ int (*old_uname)(struct utsname *u);
+
+ dlerror();
+ old_uname = dlsym(RTLD_NEXT, "uname");
+
+ if ((err = dlerror())) {
+ fprintf(stderr, "Unable to load uname: %s\n", err);
+ exit(EXIT_FAILURE);
+ }
+
+ if (!(ret = old_uname(u)))
+ strcpy(u->release, "2.6.40");
+
+ return ret;
+}
Build it into a dynamic library, the use LD_PRELOAD to load it before
your application is run:
$ gcc -shared -fPIC trapuname.c -ldl -o libtrapuname.so
$ LD_PRELOAD=./libtrapuname.so stupidapp
At least this way, you won't be carting around a local kernel patch just
for a version change :\.
--
joshc
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Re: Compiling kernel module ...
Use #if like * *#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c)) #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 33) // New socket create function #else // Old socket create function #endif LINUX_VERSION_CODE is defined somewhere in the kernel and you should get to use it easily. HTH Akash On Fri, Aug 5, 2011 at 12:34 PM, Abu Rasheda wrote: > I am compiling my driver and have run into following scenario. > > Socket create function got a new parameter in Vanila kenrel 2.6.33. while > Scientific Linux has it back ported to 2.6.32. How do I handle this kind of > situation ? so that my driver compiles for both kernel versions. > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Reboot not calling module_exit of LKM
Thanks Greg. Appreciate your reply. Regards, Ramesh On Fri, Aug 5, 2011 at 12:06 PM, Greg KH wrote: > On Fri, Aug 05, 2011 at 11:39:16AM -0700, Ramesh.P wrote: >> Hi, >> >> Good day! >> >> When a system is rebooted, the loadable kernel modules 'module_exit' >> functions are not called. I see this behavior in a custom kernel. My >> questions are >> >> a. Is this applicable in mainline/normal kernel too? > > Yes. > >> b. If yes, what are the reasons? (One reason may be, not to get into >> new problems while cleaning up the module) > > You don't need to unload a module as the machine is about to be turned > off. > >> c. Is there anyway for the kernel module to know the system is getting >> rebooted? (Apart from letting userspace to indicate the kernel >> module). > > Yes, hook to the reboot notifier. > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
trouble with __aquires(lock) __releases(lock)
Im trying to use macros from include/linux/compiler.h
and theyre giving me warnings that dont look right.
after thrashing on my own hacks, I looked to well established uses for guidance.
But make C=1 fs/file.o also gives errors, similar to mine.
What am I missing ?
or has some bitrot set in ?
202static int expand_fdtable(struct files_struct *files, int nr)
203__releases(files->file_lock)
204__acquires(files->file_lock)
205{
206struct fdtable *new_fdt, *cur_fdt;
207
208spin_unlock(&files->file_lock);
209new_fdt = alloc_fdtable(nr);
210spin_lock(&files->file_lock);
...
247int expand_files(struct files_struct *files, int nr)
248{
...
268/* All good, so we try */
269return expand_fdtable(files, nr);
270}
CHECK /home/jimc/projects/lx/linux-2.6/fs/file.c
/home/jimc/projects/lx/linux-2.6/fs/file.c:32:5: warning: symbol
'sysctl_nr_open_min' was not declared. Should it be static?
/home/jimc/projects/lx/linux-2.6/fs/file.c:33:5: warning: symbol
'sysctl_nr_open_max' was not declared. Should it be static?
/home/jimc/projects/lx/linux-2.6/fs/file.c:416:21: warning: symbol
'init_files' was not declared. Should it be static?
/home/jimc/projects/lx/linux-2.6/include/linux/spinlock.h:325:2:
warning: context problem in 'expand_fdtable': '_raw_spin_unlock'
expected different context
/home/jimc/projects/lx/linux-2.6/include/linux/spinlock.h:325:2:
context 'lock': wanted >= 1, got 0
/home/jimc/projects/lx/linux-2.6/fs/file.c:269:23: warning: context
problem in 'expand_files': 'expand_fdtable' expected different context
/home/jimc/projects/lx/linux-2.6/fs/file.c:269:23:context
'file_lock': wanted >= 1, got 0
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Compiling kernel module ...
I am compiling my driver and have run into following scenario. Socket create function got a new parameter in Vanila kenrel 2.6.33. while Scientific Linux has it back ported to 2.6.32. How do I handle this kind of situation ? so that my driver compiles for both kernel versions. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Reboot not calling module_exit of LKM
On Fri, Aug 05, 2011 at 11:39:16AM -0700, Ramesh.P wrote: > Hi, > > Good day! > > When a system is rebooted, the loadable kernel modules 'module_exit' > functions are not called. I see this behavior in a custom kernel. My > questions are > > a. Is this applicable in mainline/normal kernel too? Yes. > b. If yes, what are the reasons? (One reason may be, not to get into > new problems while cleaning up the module) You don't need to unload a module as the machine is about to be turned off. > c. Is there anyway for the kernel module to know the system is getting > rebooted? (Apart from letting userspace to indicate the kernel > module). Yes, hook to the reboot notifier. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Reboot not calling module_exit of LKM
Hi, Good day! When a system is rebooted, the loadable kernel modules 'module_exit' functions are not called. I see this behavior in a custom kernel. My questions are a. Is this applicable in mainline/normal kernel too? b. If yes, what are the reasons? (One reason may be, not to get into new problems while cleaning up the module) c. Is there anyway for the kernel module to know the system is getting rebooted? (Apart from letting userspace to indicate the kernel module). Appreciate your help and apologize if this is already answered in this forum. Thanks, Ramesh ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: can i simply "re-version" the kernel down to 2.x?
On Fri, 5 Aug 2011, Greg KH wrote: > On Fri, Aug 05, 2011 at 10:36:00AM -0400, Robert P. J. Day wrote: > > > > for reasons that don't need explaining, i need to rebuild my current > > 3.0.0... kernel so that it returns a "uname" version number of > > "2.whatever". i simply have an app i want to run that checks the > > output of "uname" and if it doesn't see a major number of "2", it goes > > a bit squirrelly. > > > > there's no *technical* reason i can see for the app to be that > > restrictive, so i was just going to hack the top level Makefile of my > > git clone and label this as a 2.99.99 kernel. is there anything that > > would break because of that kind of hackery? > > Why not just call it 2.6.40 like Fedora is doing for this very reason? i could do that as well, i just wanted to verify that manually tweaking it this way wouldn't clash with any other versioning info hidden somewhere else in the source tree. i'll know in about 10 minutes once this build is done. rday ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: can i simply "re-version" the kernel down to 2.x?
On Fri, Aug 05, 2011 at 10:36:00AM -0400, Robert P. J. Day wrote: > > for reasons that don't need explaining, i need to rebuild my current > 3.0.0... kernel so that it returns a "uname" version number of > "2.whatever". i simply have an app i want to run that checks the > output of "uname" and if it doesn't see a major number of "2", it goes > a bit squirrelly. > > there's no *technical* reason i can see for the app to be that > restrictive, so i was just going to hack the top level Makefile of my > git clone and label this as a 2.99.99 kernel. is there anything that > would break because of that kind of hackery? Why not just call it 2.6.40 like Fedora is doing for this very reason? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
can i simply "re-version" the kernel down to 2.x?
for reasons that don't need explaining, i need to rebuild my current 3.0.0... kernel so that it returns a "uname" version number of "2.whatever". i simply have an app i want to run that checks the output of "uname" and if it doesn't see a major number of "2", it goes a bit squirrelly. there's no *technical* reason i can see for the app to be that restrictive, so i was just going to hack the top level Makefile of my git clone and label this as a 2.99.99 kernel. is there anything that would break because of that kind of hackery? rday -- Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Mapped more than Cached in /proc/meminfo
Hi, I am trying to analyze memory usage on my system. As first step I am monitoring /proc/meminfo. Surprisingly I see Mapped value is more than Cached. So in which case is it possible to have Mapped more than Cached ? Regards, ~/ ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Creating sparse file on XFS and EXT3 has different results
Apologies for the top post. I simply forgot to not do that. On Aug 5, 2011 8:11 AM, "Greg Freemyer" wrote: > > There are no "specs" as to how a sparse file is handled in response to writes. > > Sparse is mostly beneficial when the holes are very large. > > If an app really wants to have minimal on disk space, you should pre-allocate space with fallocate. > > You may even need to hole punch after the writes. Both xfs and ext4 support both fallocate and hole punching. (I don't know the userspace call to hole punch. I think its a relatively new feature for ext4.) > > Greg > > On Aug 4, 2011 10:16 PM, "Ashish Sangwan" wrote: Greg ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Creating sparse file on XFS and EXT3 has different results
There are no "specs" as to how a sparse file is handled in response to writes. Sparse is mostly beneficial when the holes are very large. If an app really wants to have minimal on disk space, you should pre-allocate space with fallocate. You may even need to hole punch after the writes. Both xfs and ext4 support both fallocate and hole punching. (I don't know the userspace call to hole punch. I think its a relatively new feature for ext4.) Greg On Aug 4, 2011 10:16 PM, "Ashish Sangwan" wrote: ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
how to freeze the 2.6 kernel on SMP m/c
Hi,
Could you please suggest how to freeze the 2.6 kernel(SMP m/c) with
my own dlkm with less number of code.
I tried the below mentioned code snippet, it hangs only the terminal
on which i executed the insmod command.
Please correct the below code to freeze whole kernel.
#include
#include
#include
#include
int init_module(void)
{
spinlock_t lock = SPIN_LOCK_UNLOCKED;
while (1) {
spin_lock(&lock);
msleep(100);
}
//spin_unlock(lock);
printk(KERN_INFO "Hello world :).\n");
return 0;
}
void cleanup_module(void)
{
printk(KERN_INFO "Goodbye world :(.\n");
}
Thanks and Regards,
Sandeep
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