Is It Time For A Modem Funeral?

Hi all,

In my work, I'd like to spawn separate kernel threads (tasks) to execute syscall asynchronously. Specifically, a user thread issues a syscall, goes into kernel, save the syscall number and arguments somewhere in the kernel address space, but does not execute the syscall. A kernel thread which is different from the user thread, will fetch the syscall number and arguments to execute the syscall on behalf of the user thread.
But for file operations such as read, the kernel thread is not aware of the open files of the user threads. For example, if the user thread opens a file and get a file descriptor, then it issue a read() syscall. The kernel thread cannot execute the read() on behalf of the user thread by just using the file descriptor. Thus I need some way to allow the kernel thread share the open files information with the user thread, such that the kernel thread will have the context of the open file to execute read(). I tried to pass the files_struct of the user thread's task_struct to the kernel thread, but it didn't help, read() returns a EFAULT error.
Can anyone give me some suggestions on how to make a kernel thread share the open files with a user thread? Or more straightforward how to execute the read() syscall in the example above in kernel thread? Thank you very much!

--Louis

Hi guys,

I'm new to the forum and the first problem appeared, hope u guys can help me out!


Just changed my system from Windows to Linux and have some issues to get my Wifi Stick
Fritz! WLAN USB N v 2 working.

1. I downloaded the newest drivers for Win64-Bit from the AVM Homepage.
2. Started ndiswrapper Selected the fwlan64.inf -> Clicked on install.
3. Error Message appears :
modprobe: FATAL: Module ndiswrapper not found
4. Uninstalled ndiswrapper (thought probably and older version could fix this was reading on some Ubuntu Forum cause i couldnt find anything for Ziron)

Any help appreciated!

Thank you so much!

Edit: Some more info

System Log:

Quote:
stani-System-Product-Name kernel: [ 2085.487551] usb 2-1.6: USB disconnect, device number 13
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.452762] usb 2-1.6: new high-speed USB device number 14 using ehci-pci
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.549669] usb 2-1.6: New USB device found, idVendor=057c, idProduct=8501
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.549674] usb 2-1.6: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.549677] usb 2-1.6: Product: FRITZ!WLAN USB Stick N v2
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.549680] usb 2-1.6: Manufacturer: AVM Berlin
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.549682] usb 2-1.6: SerialNumber: 246511430F18
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.624607] usb 2-1.6: reset high-speed USB device number 14 using ehci-pci
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.719007] ieee80211 phy4: rt2x00_set_rt: Info - RT chipset 5592, rev 0222 detected
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.756314] ieee80211 phy4: rt2x00usb_vendor_request: Error - Vendor Request 0x09 failed for offset 0x0000 with error -32
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.756320] ieee80211 phy4: rt2x00lib_probe_dev: Error - Failed to allocate device
Feb 12 16:34:23 stani-System-Product-Name kernel: [ 2086.756349] rt2800usb: probe of 2-1.6:1.0 failed with error -32
Feb 12 16:34:23 stani-System-Product-Name mtp-probe: checking bus 2, device 14: "/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.6"
Feb 12 16:34:23 stani-System-Product-Name mtp-probe: bus: 2, device: 14 was not an MTP device
Feb 12 16:34:24 stani-System-Product-Name usb_modeswitch: switched to 057c:ffffffff on 002/013
uname -a

Quote:
Linux stani-System-Product-Name 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
stani@stani-System-Product-Name:~$
lsusb
Quote:
Bus 002 Device 006: ID 0b05:179c ASUSTek Computer, Inc.
Bus 002 Device 014: ID 057c:8501 AVM GmbH
Bus 002 Device 004: ID 1ea7:1005
Bus 002 Device 003: ID 046d:c326 Logitech, Inc.
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 006 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 005 Device 002: ID 05e3:0727 Genesys Logic, Inc. microSD Reader/Writer
Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Hi.


I'm using smstools3 and Sony Ericsson Phones to send SMS. My system did work well with 4 phones, now I want to connect 20.
The issue is that each phone generates two ttyACMXX devices using cdc_acm driver, and for limitations the driver supports up to 32 ACM devices

Code:

Aug 31 09:51:19 smsgw kernel: cdc_acm 2-2:1.1: ttyACM31: USB ACM device
Aug 31 09:51:19 smsgw kernel: cdc_acm 2-2:1.3: ttyACM32: USB ACM device
Aug 31 09:51:19 smsgw kernel: usbco  registered new driver cdc_acm
Aug 31 09:51:19 smsgw kernel: drivers/usb/class/cdc-acm.c: v0.25:USB Abstract Control Model driver for USB modems and ISDN adapters
Aug 31 09:51:19 smsgw kernel: usbco  registered new driver cdc_ether
Aug 31 09:51:19 smsgw kernel: usb 2-2: unsupported MDLM descriptors
Aug 31 09:52:01 smsgw kernel: cdc_acm 3-1:1.0: no more free acm devices

From the ttyACM devices created by the driver I only use the first one..

So I was wondering if it is possible to remove a ttyACM from /sys/class/tty/ttyACM1

I tried unlink /dev/ttyACM1, but it persist as a device on /sys/class/tty/

The devices are removed if I disconnect the phone, So I think would be possible also that the driver only create one ttyACM device..

Please guide me...

Thanks in advance.

I am using phpVirtualBox, and everything is working perfectly. Then something changes, and I get the following error:
Code:

Could not connect to host (http://127.0.0.1:18083/)

I reboot the physical machine, or execute /etc/init.d/vboxweb-service restart, and then everything works for a while.

According to http://sourceforge.net/p/phpvirtualb...onnect-to-host, there are three reasons why this will happen.
Quote:
This indicates that phpVirtualBox could not connect to the vboxwebsrv server. Either the location setting in config.php is wrong, vboxwebsrv is not running on the VirtualBox host, or SELinux is blocking access to vboxwebsrv. If you have SELinux enabled
As shown below, it is not reason 2 or 3.

Code:

[root@devserver ~]# service vboxweb-service status
Checking for VBox Web Service ...running
[root@devserver ~]# service vboxdrv status
VirtualBox kernel modules (vboxdrv, vboxnetflt, vboxnetadp, vboxpci) are loaded.
[root@devserver ~]# service vboxautostart-service status
Usage: /etc/init.d/vboxautostart-service {start|stop}
[root@devserver ~]# service  vboxballoonctrl-service status
Checking for VBox watchdog service ...not running
[root@devserver ~]# sestatus
SELinux status:                 enabled
SELinuxfs mount:                /selinux
Current mode:                   permissive
Mode from config file:          permissive
Policy version:                 24
Policy from config file:        targeted
[root@devserver ~]#

Thus it must be that the location setting in config.php is wrong. config.php has the following default settings, and I left them as is.

Code:

/* SOAP URL of vboxwebsrv (not phpVirtualBox's URL) */
var $location = 'http://127.0.0.1:18083/';
...
// Host / ip to use for console connections
#var $consoleHost = '192.168.1.40';

According to http://sourceforge.net/p/phpvirtualb...-configuration, "If VirtualBox and phpVirtualBox are on the same physical host, you may leave the $location setting alone". VirtualBox and phpVirtualBox are definitely on the same physical machine.

Please provide recommendations.

Hi everyone (i hope this is the right section)

Im trying to install the RT patch preempt_rt 3.18.9 im running Ubuntu 14.04 with kernel v 3.16

i installed the rt patch "patch-3.18.9-rt5.patch" and also a new kernel "3.18.9" i patched the patch file with

patch -p1 < patch-3.18.9.patch

but there is somthing i don't know about linking folders of old kernel and new kernel, i searched about it and found

rm -rf linux && ln -s /usr/src/linux-3.18.9 linux && cd /usr/src/linux

then

make oldconfig

then

make menuconfig

i selected Full preemptive kernel then

make

then this error

cc1: some warnings being treated as errors make[2]: * [kernel/locking/locktorture.o] Error 1 make[1]: * [kernel/locking] Error 2 make: *** [kernel] Error 2


So..... Any help?? can someone walk me through this

or any other real time patch, Thanx.. plzzzzzz

I am going to attempt to dual boot both fedora 17 and fedora 21, as my printer can print from FC17 but not from FC21 - posted about this issue in the hardware forum.

I am rather surprised at the level of competence of people posting here, even though it says newbie forum - so I think that this is possibly where I belong too.

I have set up grub to see my fedora 17 kernel - the only problem is, that the root filesystem needs to belong to the fedora 17 kernel as opposed to the fedora 21 kernel. I can't see myself changing fc 21's fstab to have the old lv root device mounted - as /etc belongs to the root partition of fc 21.

I did change the device to reflect the old kernel's root lv partition in the /etc/fstab (fc17), but this doesn't seem to do it.

Does someone know what I am missing?

I am installing VirtualBox on Centos per http://www.digitesters.com/centos-in...adless-system/, and I don't understand the very end. Seems like Line 5 is not needed as it is already done on Line 4, right?

Code:

# mkdir /data/virtual_machines/vbox/vbusbfs
# chown vboxuser.vboxusers /data/virtual_machines/vbox/vbusbfs
# chmod 775 /data/virtual_machines/vbox/vbusbfs
# echo "none /data/virtual_machines/vbox/vbusbfs usbfs rw,devgid=$(awk -F : '/vboxusers/ {print $3}' /etc/group),devmode=664 0 0" >> /etc/fstab
# echo "none /data/virtual_machines/vbox/vbusbfs usbfs rw,devgid=$(awk -F : '/vboxusers/ {print $3}' /etc/group),devmode=664 0 0" >> /etc/fstab
# mount -a

I executed the above script (except didn't execute Line 5, and my user:group is vbox:vbox and not vboxuser.vboxusers, and the folder is at /home/vbox and not /data/virtual_machines/vbox), and the following was added to /etc/fstab. Please explain what Line 4 did and what the below line in my fstab file means.
Code:

none /home/vbox/vbusbfs usbfs rw,devgid=496
504,devmode=664 0 0

I then executed mount -a, and got the following response. The part about /var/www/main/ayb_resources and /var/www/main/ayb_cache does not exist is probably some old stuff which I can get rid of, but I am particularly interested in "mount point 0 does not exist" as it seems to be related to the above.

Code:

[root@devserver vbox]# mount -a
mount: special device /var/www/main/ayb_resources does not exist
mount: special device /var/www/main/ayb_cache does not exist
mount: mount point 0 does not exist
[root@devserver vbox]#

My total fstab file is as follows:

Code:

[root@devserver vbox]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 19 05:57:56 2014
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/VolGroup-lv_root /                       ext4    defaults        1 1
UUID=xxx-xxx-xxx-xxx-xxx /boot                   ext4    defaults        1 2
/dev/mapper/VolGroup-lv_home  /home                  ext4    defaults        1 2
/dev/mapper/VolGroup-lv_mysql /var/lib/mysql         ext3    barrier=0       1 2
/dev/mapper/VolGroup-lv_swap swap                    swap    defaults        0 0
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/home/public/lib /var/www/main_lib/ayb_application/lib none bind
/var/www/main/html /var/www/main_lib/html none bind
/var/www/main/ayb_resources /var/www/main_lib/ayb_resources none bind
/var/www/main/ayb_cache /var/www/main_lib/ayb_cache none bind
none /home/vbox/vbusbfs usbfs rw,devgid=496
504,devmode=664 0 0
[root@devserver vbox]# mount -a
mount: special device /var/www/main/ayb_resources does not exist
mount: special device /var/www/main/ayb_cache does not exist
mount: mount point 0 does not exist
[root@devserver vbox]#

I wanted to delete a couple of files, so I did. Then I noticed that they were "write-protected". What does that mean? Why was I able to delete the files considering I wasn't the owner and the files did not have group write permission?

Code:

[Michael@devserver backup_database]$ ls -l
total 4344
-rw-r--r--. 1 apache apache   50639 Feb  6 05:42 2015_02_06_05_42_01.sql
-rw-r--r--. 1 apache apache  654623 Feb  6 05:45 2015_02_06_05_45_54.sql
-rw-r--r--. 1 apache apache 3738269 Feb  6 05:49 2015_02_06_05_49_02.sql
[Michael@devserver backup_database]$ rm *
rm: remove write-protected regular file `2015_02_06_05_42_01.sql'? y
rm: remove write-protected regular file `2015_02_06_05_45_54.sql'? y
rm: remove write-protected regular file `2015_02_06_05_49_02.sql'? y
[Michael@devserver backup_database]$ ls -l
total 0
[Michael@devserver backup_database]$

I am new to drivers development under linux kernel. After starting with the simple examples from the book Linux Device Drivers v3, I realised that the block driver API has been totally changed since the kernel 2.6.31 or maybe later versions, and I couldn't find any documentation about the new API and how to use it. There are just some few comments in the source code.

After struggling for one month I almost had something working but few parts are missing or I misunderstood something.

Here is the situation :

After fetching the request with blk_fetch_request(q), I use the macro __rq_for_each_bio for handling the full request
To transfer the segments one by one I use the macro bio_for_each_segment(bvec, bio, i) that loops over all the segments in a bio

My question is :

I need to do some DMA from/to my device (the dma engine is within the device), that's why I need some address that I could use it to DMA from/to
Which buffer should I use ? for the moment I use the buffer returned by char *buffer=bio_data(bio), Does "buffer" corresponds to the physical buffer that I can use for DMA
How to end the request in this case ? using __blk_end_request_cur(req, 0) ? or using __blk_end_request(req, 0, bytes) ?

If you don't have an answer to any of these questions, where can I find a useful documentation for the new API of the block device drivers.

Hi guys prob a silly question...
i only just read now that linux kernel v4 was released about 11 days ago...can any distros upgrade there kernel to 4 or only specific ones?

Is there really a huge benefit in doing so?

should i just lookup the information in the distros web site?