> -----Original Message----- > From: kernelnewbies-bounces@xxxxxxxxxxxxxxxxx [mailto:kernelnewbies- > bounces@xxxxxxxxxxxxxxxxx] On Behalf Of kernelnewbies- > request@xxxxxxxxxxxxxxxxx > Sent: Wednesday, June 20, 2012 11:33 PM > To: kernelnewbies@xxxxxxxxxxxxxxxxx > Subject: Kernelnewbies Digest, Vol 19, Issue 39 > > Send Kernelnewbies mailing list submissions to > kernelnewbies@xxxxxxxxxxxxxxxxx > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > or, via email, send a message with subject or body 'help' to > kernelnewbies-request@xxxxxxxxxxxxxxxxx > > You can reach the person managing the list at > kernelnewbies-owner@xxxxxxxxxxxxxxxxx > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Kernelnewbies digest..." > > > Today's Topics: > > 1. RE: A confusion about invoking my syscall (Jeff Haran) > 2. Re: Sysfs class attribute problem (Jeshwanth Kumar N K Jeshu) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 20 Jun 2012 16:58:30 +0000 > From: Jeff Haran <jharan@xxxxxxxxxxxxxx> > Subject: RE: A confusion about invoking my syscall > To: ?? <wangzhe5004@xxxxxxxxx> > Cc: kernelnewbies <kernelnewbies@xxxxxxxxxxxxxxxxx> > Message-ID: > <4AB110E2FA959F41AC8480E84516371105B80D@xxxxxxxxxxxxxxxxxxxxxx> > Content-Type: text/plain; charset="iso-2022-jp" > > > > From: ?? [mailto:wangzhe5004@xxxxxxxxx] > Sent: Wednesday, June 20, 2012 1:16 AM > To: Jeff Haran > Cc: kernelnewbies > Subject: Re: A confusion about invoking my syscall > > > 2012/6/20 Jeff Haran > <jharan@xxxxxxxxxxxxxx<mailto:jharan@xxxxxxxxxxxxxx>> > > > From: ?? [mailto:wangzhe5004@xxxxxxxxx<mailto:wangzhe5004@xxxxxxxxx>] > Sent: Monday, June 18, 2012 9:32 PM > To: Jeff Haran > Cc: kernelnewbies > Subject: Re: A confusion about invoking my syscall > > > 2012/6/19 Jeff Haran > <jharan@xxxxxxxxxxxxxx<mailto:jharan@xxxxxxxxxxxxxx>> > > > From: kernelnewbies-bounces@xxxxxxxxxxxxxxxxx<mailto:kernelnewbies- > bounces@xxxxxxxxxxxxxxxxx> [mailto:kernelnewbies- > bounces@xxxxxxxxxxxxxxxxx<mailto:kernelnewbies- > bounces@xxxxxxxxxxxxxxxxx>] On Behalf Of ?? > Sent: Monday, June 18, 2012 6:40 PM > To: kernelnewbies > Subject: A confusion about invoking my syscall > > Hello everyone: > > I append a simple syscall in kernel. and the function is as > follows: > > asmlinkage long sys_mysyscall(long data) > { > printk("This is my syscall!\n"); > return data; > } > > and i test it sucessfully in user space . and the test program: > > #include <linux/unistd.h> > #include <syscall.h> > #include <sys/types.h> > #include <stdio.h> > > > > int main(void) > { > long n = 0,m = 0,pid1,pid2; > n = syscall(345,190);// #define __NR_mysyscall 345 > printf("n = %ld\n",n); > pid1 = syscall(SYS_getpid); //getpid > printf("pid = %ld\n",pid1); > pid2 = syscall(20); //getpid > printf("pid = %ld\n",pid2); > return 0; > } > and the result: > n = 190 > pid = 4097 > pid = 4097 > > but if the test program is: > #include <linux/unistd.h> > #include <syscall.h> > #include <sys/types.h> > #include <stdio.h> > > > > int main(void) > { > long n = 0,m = 0,pid1,pid2; > n = syscall(345,190);// #define __NR_mysyscall 345 > printf("n = %ld\n",n); > m = syscall(SYS_mysyscall,190); > printf("m = %ld\n",m); > pid1 = syscall(SYS_getpid); //getpid > printf("pid = %ld\n",pid1); > pid2 = syscall(20); //getpid > printf("pid = %ld\n",pid2); > return 0; > } > and the result: > wanny@wanny-C-Notebook-XXXX:~/syscall/src$ gcc test1.c > test1.c: In function ?main?: > test1.c:13:14: error: ?SYS_mysyscall? undeclared (first use in this > function) > test1.c:13:14: note: each undeclared identifier is reported only once > for each function it appears in > > > why i can't invoke my syscall with "SYS_mysyscall"? > > Thanks in advance! > Because it appears you never defined the symbol SYS_mysyscall. > I think so,but where shoud i defne the symbol SYS_mysyscall ? > and where is the symbol SYS_getpid defined? > On my system /usr/include/bits/syscall.h, which is being included in > your program because it includes syscall.h. > 83 #define SYS_getpid __NR_getpid ?so SYS_getpid is > replaced by __NR_getpid. and __NR_getpid was defined in the > kernel(arch/x86/include/asm/unistd_32.h). and my syscall was also > defined there.#define SYS_mysyscall __NR_mysyscall, i don't kown why it > doesn't works. > > My sources contain no reference to SYS_mysyscall nor __NR_mysyscall, so > I assume you?ve added them to the Linux include files that you built > your module from. > > User space programs like your main() program above generally aren?t > going to include Linux source tree include files. When you include > <syscall.h> from a user space program in a typical development > environment, the compiler is by default going to look for syscall.h in > /usr/include, not in the Linux source tree where presumably you?ve made > your modifications. Of course you can always tell the compiler to look > there using the -I command line option to gcc, if you want to. The > usual practice however is to keep kernel code and user code include > files completely separate. That means some duplication of effort, like > having to define SYS_mysyscall in two different places, but that?s the > usual practice because most people aren?t building kernels and thus > haven?t installed the kernel source include files. > > Jeff Haran > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/2012 > 0620/4287a36b/attachment-0001.html > > ------------------------------ > > Message: 2 > Date: Wed, 20 Jun 2012 23:32:12 +0530 > From: Jeshwanth Kumar N K Jeshu <jeshkumar555@xxxxxxxxx> > Subject: Re: Sysfs class attribute problem > To: anish singh <anish198519851985@xxxxxxxxx> > Cc: kernelnewbies@xxxxxxxxxxxxxxxxx > Message-ID: > <CAC-LjFsrQk4FQab-Yb=ZKExd_FT9dB0X_BvLK6R- > oGuOpVXtPg@xxxxxxxxxxxxxx> > Content-Type: text/plain; charset="iso-8859-1" > > Hello > > Thank you anish for the reply, the code is I pasted below. > [code-starts] > > #include <linux/init.h> > #include <linux/module.h> > #include <linux/kernel.h> > #include <linux/fs.h> > #include <linux/device.h> > #include <linux/sysdev.h> > #include <linux/major.h> > #include <asm/uaccess.h> > #include <linux/slab.h> > #include <linux/cdev.h> > #include <linux/kdev_t.h> > > static char *gvar = "BeHonest"; Your gvar doesn't point to any allocated or statically allocated memory..... > // Store and Show functions...... > static ssize_t attr1_store(struct class *cls, struct class_attribute > *attr, const char *buf, size_t count); > static ssize_t attr1_show(struct class *cls, struct class_attribute > *attr, > char *buf); > > static struct class_attribute pwm_class_attrs[] = { > __ATTR(attr1, S_IRUGO | S_IWUSR , attr1_show, attr1_store), > __ATTR_NULL > }; > > static struct class pwm_class = > { > .name = "dev_jes", > .owner = THIS_MODULE, > .class_attrs = pwm_class_attrs > }; > > > static int hello_init(void) > { > class_register(&pwm_class); > printk("In hello_init function \n"); > > return 0; > } > > static ssize_t attr1_show(struct class *cls, struct class_attribute > *attr, > char *buf) > { > > printk("In attr1_show function\n"); > return sprintf(buf, "%s\n", gvar); > } > > static ssize_t attr1_store(struct class *cls, struct class_attribute > *attr, > const char *buf, size_t count) > { > printk("the string is : %s\n",buf); > printk("In attr1_store function\n"); > return 1; > //return sprintf(gvar, "%s\n", buf); --- If I put this > line I > am getting ERROR :( Ofcourse you'll....! gvar isn't allocated memory... you are trying to over write a read only memory area. > } > > > static void hello_exit(void) > { > class_unregister(&pwm_class); > printk("In hello_exit function \n"); > } > > module_init(hello_init); > module_exit(hello_exit); > > MODULE_LICENSE("GPL"); > MODULE_AUTHOR("Jeshwanth"); > MODULE_DESCRIPTION("Learning sysfs"); > > [code-ends] > > echo "jeshu" > /sys/class/dev_jes/attr1 > > And If I pass the command to atttribute I got result below in dmesg. > > [ 3435.613057] the string is : jeshu > [ 3435.613061] > [ 3435.613066] In attr1_store function > [ 3435.613072] the string is : eshu > [ 3435.613074] > [ 3435.613078] In attr1_store function > [ 3435.613083] the string is : shu > [ 3435.613085] > [ 3435.613088] In attr1_store function > [ 3435.613093] the string is : hu > [ 3435.613095] > [ 3435.613098] In attr1_store function > [ 3435.613103] the string is : u > [ 3435.613105] > [ 3435.613108] In attr1_store function > [ 3435.613113] the string is : > [ 3435.613115] > [ 3435.613118] In attr1_store function > > > So please help me how to read the attribute in store function.. Thanks > :) > > > On Tue, Jun 19, 2012 at 4:02 PM, anish singh > <anish198519851985@xxxxxxxxx>wrote: > > > On Tue, Jun 19, 2012 at 3:14 PM, jeshwanth Kumar N K > > <jeshkumar555@xxxxxxxxx> wrote: > > > Hello all > > > > > > I am new to sysfs interface ans I read about in mochel's > documentation. > > And > > > doing some experiements on it. Let's come to Tue problem, in my > module I > > > have a global variable type char* myglobal and it s static, I am > putting > > > that value in my one and only class attribute using show function. > But > > for > > > the same if I a user put some value in to the using echo or > something, > > the > > > attribute value is not changing. And one more thing s after I > passed the > > > value to the attribute my system not shutting down :( . Please help > me > > how > > > to read values. > > Why don't you post your code?As that will really help and moreover as > > this is your code > > you won't be breakign any law set by your company. > > > > > > // in store function I am doing this: > > > Myglobal = bus; > > > > > > Sent from my HTC > > > > > > > > > > > > > > > _______________________________________________ > > > Kernelnewbies mailing list > > > Kernelnewbies@xxxxxxxxxxxxxxxxx > > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > > > > > > -- > Regards > Jeshwanth Kumar N K > +91-7411483498 > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/2012 > 0620/72d70af2/attachment.html > > ------------------------------ > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > End of Kernelnewbies Digest, Vol 19, Issue 39 > ********************************************* ::DISCLAIMER:: ---------------------------------------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. 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