I am currently facing a problem in locating the syscall_table.S file in my arch/x86/kernel/ directory. In the online tutorail that i am following, it is gievn that i will find the file in this location. I am using linux-3.11.10. Please tell me how to locate this file. However, I have found this file in some other folders. If i were to modify one of these,which one should I modify ?
The following folders have syscall_table.S :
arch/microblaze/kernel
arch/m32r/kernel
arch/avr32/kernel
arch/parisc/kernel
Your question isn't very specific about what exactly you are trying to do.
sys_call_table is defined in arch/x86/kernel/syscall_64.c
The syscall entry is located in arch/x86/kernel/entry_64.S
routines are associated with their syscall number in include/uapi/asm-generic/unistd.h and arch/x86/syscalls/syscall_64.tbl
You might also want to look at include/linux/syscalls.h.
Related
Clarification: the directory /george/ exists when I am given the task, and I do know how to read the attribute in cli showing that it is a directory. The balance of the path requested does not exist, so the only way I can tell if 'poppet' is a file or directory is by convention. This question comes from an issue I had with interpretation of this line, so am interested in knowing if there is a convention. This occurred using Ubuntu, but would be relevant in any distro, methinks.
TLDR
I need to get paths to system directories like "Screenshots":
On an English system. I can just use this one:
C:/Users/User/Pictures/Screenshots
How do I get the path to "Screenshots" directory on a non-English system?
C:/Users/User/Pictures/[NAME]
Description
I have a file manager app, it displays system directories and loads them on click.
The app can run system commands via Powershell and use Node.js (preferred)
Problem
The problem is, it only works if the system has English system language.
Currently, to resolve the "Screenshots" directory path, the app simply joins the User directory with the word "Screenshots"
const pictures = electronRemote.app.getPath('pictures')
const screenshots = PATH.join(pictures, 'Screenshots')
link to the line in code
Expectedly, the C:/Users/User/Screenshots path only exists on English systems.
One way to solve this is to use short names, at least on Windows, I know that system directories have short names like SCREEN~1 and WALLPA~1 for Screenshots and Wallpapers directories, but if I use these names the paths will look like this:
C:/Users/User/SCREEN~1 instead of C:/Users/User/Screenshots throughout the app.
And even if I were to run these paths through a function to convert it to readable name, how would I know which word to replace it with? I need to get the name in the system's language.
Are these translations stored somewhere on the system? Can I just retrieve the translated directory name and use that in the code above?
Question
How do I make it to get / resolve the actual path of system directories like Screenshots and Wallpapers, independently of system locale?
If you know how to do it, could you please suggest the solution for all platforms (Win, Mac, Linux)?
Should I just use the short names like SCREEN~1 and then automatically replace all the occurrences in UI and also filter all paths through a function that replaces this short name with the actual path throughout the whole app? Seems like a lot of work, this approach
I'm trying to vusb-analyzer.
It requires *.mon log file.
How can I make usbmon log file (*.mon)?
https://www.kernel.org/doc/Documentation/usb/usbmon.txt
The document you linked in your question is actually the answer, please see the sections 1-3.
In section 3, it says:
# cat /sys/kernel/debug/usb/usbmon/0u > /tmp/1.mon.out
This will create a text file 1.mon.out. Its structure is also described in the same document.
Now, how do I know that this is the file to be opened by vusb-analyzer? From what I see, the website of this project doesn't make it clear what the *.mon file is.
However, you can see it in the source code:
https://github.com/scanlime/vusb-analyzer/blob/master/VUsbTools/Log.py#L498
It clearly states, that the program uses the syntax described in the document that you already know:
https://www.kernel.org/doc/Documentation/usb/usbmon.txt
The name of your file doesn't really matter, but if you want it to end with ".mon", you could simply use:
# cat /sys/kernel/debug/usb/usbmon/0u > ~/somefile.mon
Two warnings:
The line with cat I posted here is just an example and in order to use it, you will need to follow the steps in the document (it won't work without enabling usbmon first)
vusb-analyzer hasn't been updated for years and I wasn't able to run it on my machine. Its website mentions Ubuntu 8.10 so I wouldn't be surprised if others had problems running it, too. (For example, in order to reproduce your problem, provide more help).
I want to add custom syscall to freebsd(school work). I google hundreds of time. there is no right solution for it.
my homework is: "Add custom syscall to freebsd kernel and recompile the kernel and use it".
finally I find that I should follow instructions in these two pages:
1 : http://www.onlamp.com/pub/a/bsd/2003/10/09/adding_system_calls.html
then
2: https://www.freebsd.org/doc/en/books/handbook/kernelconfig-building.html
will it shows errors in compile time:
<sys/parma.h> no such file or directory
<sys/kern.h> no such file or directory
<sys/syscallargs.h> no such file or directory
I removed these three header include form my file then recompile it. now shows other errors like: MAXCPU undeclered in pcpu.h file.
what I missed? how can I do my school work?
NOTE: I use freebsd8 in vbox
Look at what the error messages say; the files don't exist.
The first include file is a typo; it's param.h, not parma.h!
There is no kern.h. Maybe you mean sys/kernel.h?
Idem for syscallargs.h. Do you perhaps mean syscall.h?
You can find header files with e.g:
find /usr/src/sys/ -type f -name '*.h'|grep 'sys/.*kern.*\.h'
/usr/src/sys/ofed/include/linux/kernel.h
/usr/src/sys/dev/netmap/netmap_kern.h
...
Update: More important is determining which includes you actually need.
FreeBSD has pretty good documentation. If you want to use a kernel function or data-structure, it is probably covered in section 9 of the manual pages.
You can list all the manual pages in that section with ls /usr/share/man/man9/ | less. Or you can use the apropos command.
Since you want to implement a syscall, start with e.g.
apropos syscall
It will return:
SYSCALL_MODULE(9) - syscall kernel module declaration macro
syscall(2), __syscall(2) - indirect system call
It seems to me that the first one could be relevant to your assignment. (The second one is how to call a system call from user space.) So read it with man SYSCALL_MODULE. Or read it online.
Note that:
A minimal example for a syscall module can be found in
/usr/share/examples/kld/syscall/module/syscall.c.
That example should be enough to get you started on writing your own system call module...
Well take a look at share/examples/kld/syscall for a complete implementation as a module.
Adding a new file to teh kernel is left as an exercise for the reader.
Here is a hint: find the newest added file within kern/* subdir AND CHECK WHAT COMMITS WERE DONE TO MAKE IT COMPILE.
In fact you could have done exactly the same with syscall: FIND THE NEWEST ADDED SYSCALL AND CHECK HOW IT WAS ACHIEVED.
All this is available in svn/git repository history.
I am using a command in the proc file system which is the following
echo 0 > /proc/sys/net/ipv4/ip_forward
Note: I don't want to know the basic of the command written above, I want what all happens when it goes inside the kernel. As, I want to implement one of the /proc file.
Now if I want to trace the code right from when the 0 is echoed in the file-system then how to go about it. I mean if I want to trace what happens when I do this.
I want to see where in the kernel code this 0 is accepted and in which value does it get stored inorder to make the changes. Please, can somebody tell what all happens when you call this command. I want in detail explain. I don't want the description of the command.
Any related article on how it changes the kernel parameters is also fine.
I have read this but, not explained there. http://www.linuxjournal.com/article/8381
Thanks
search through linux tree (especially network stack) for create_proc_entry function. Figure out what file creates ip_forward (it must be in ip4v drivers) from name passed to create_proc_entry.
When you find the file, look at where proc_dir_entry structure is created and what functions are assigned to its read_proc, write_proc members.