Hi Rajat, On Tue, Jan 11, 2011 at 2:10 AM, Rajat Sharma <[email protected]> wrote: >> is there any procedure in kernel to check for the interrupt vector number >> which caused it to be invoked? > Its actually very architecture dependent, on x86, its 'int $0x80' > which causes user space to call system calls handlers. Recent intel > architectures have callgate mechanism to enter into system call, look > for sysenter instruction. > Anyways, are you interested in interrupt number or the system call number? > >> i mean like one of my friends said that when kernel is about to restart a >> syscall then it raises signal -ERESTARTSYS signal for signal handler. > > Thats totally wrong. Like any other error code, its just an error code > which waiting API return if process was interrupted while waiting on > semaphore, e.g.
On the ARM platform, at least, if a syscall (like ioctl) returns -ERESTARTSYS, then the ioctl will be reissued after the signal handler runs. I know this to be true, as I've verified it's functionality emperically. This is further supported by the kernel documentation http://lxr.linux.no/linux+v2.6.37/Documentation/DocBook/kernel-hacking.tmpl#L346 Dave Hylands _______________________________________________ Kernelnewbies mailing list [email protected] http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
