January 2014 - kernelnewbies@kernelnewbies.org

Linux ARM, does schedule() jumps to user space ?
by Mj Embd Jan. 3, 2014

Jan. 3, 2014

Hi, A very basic question. AFAIK schedule() selects the next process to run. Now once it has selected the process, and say if the process is a user space or kernel space one. how does the switch to user happens, a) Is it in schedule function . it has to be a arch level function called from schedule() b) or Else where, so is there a umberlla function like somefunc() { task_ptr = schedule(); switch_to(task_ptr) ... } Can someone explain this

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Bug 12665
by John de la Garza Jan. 2, 2014

Jan. 2, 2014

I found a bug that appears to be simple to fix. I assume I am missing something. here is a link to the bug description: https://bugzilla.kernel.org/show_bug.cgi?id=12665 the man page for the function in the bug report mentions that linux does not impliment the desired functionality It seems like it is accepted as working the way it does, and at the same time it is reported in bugzilla as a current bug. What am I missing?

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USB device driver not binding to device
by Valentina Manea Jan. 1, 2014

Jan. 1, 2014

Hi, I am working on the USB/IP drivers in the staging directory and bumped into an issue with one of the drivers. usbip-host is declared as struct usb_driver (so, an USB interface driver). My task was to transform it to struct usb_device_driver - in this way, instead of binding each interface to the driver, the whole device would be bound to the driver. The binding is made from userspace via the bind file of the driver [1] and using libsysfs. With the old version of the driver, one would write something like 1-1:1.0 to bind interface 0 of device with bus ID 1-1. However, with the new version of the driver, using the same syntax for device identification (1-1:1.0), this binding fails: * libsysfs doesn't give much info about the error * echo-ing the ID into bind file as shown in [1] doesn't work in either case; on the other hand, I can succesfully unbind the device from the default driver (usb-storage in this case) using the same mechanism * I have a printk in the probe function of the driver - it seems it doesn't even get there. I am missing something but have no clue where to look anymore. Thanks, Valentina [1] http://lwn.net/Articles/143397/

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