- kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Problem with a UDP server implements
by jiangtao.jit Oct. 21, 2011

Oct. 21, 2011

Hi: I'm writing a UDP server and meet a problem the UDP server program is run on a box with single card but has multi ip: like eth0 10.0.0.1 eth0:1 10.0.0.2 eth0:2 11.0.0.1 I bind the server socket with INADDR_ANY when a client send a packet to 10.0.0.2(the eth0:1 's ip) the server can recieve the packet and reply, but the client can't recieve the server's response I use wireshark to capture the response packet and found that the server use 10.0.0.1(the eth0 's ip) as saddr in the response packet I expected it to be 10.0.0.2 but it's not my question : is there any way to let the UDP server relpy just use the ip it receieved the request ? It's : when a client send a request to 10.0.0.1(eth0); the server use 10.0.0.1 to response and another client send a request to 10.0.0.2(eth0:1); the server use 10.0.0.2 to response Thanks. 2011-10-15 jiangtao.jit

4 10

Re: Getting physical address of memory allocated by vmalloc()
by Dave Hylands Oct. 21, 2011

Oct. 21, 2011

Hi Jacky, On Oct 20, 2011 6:32 PM, "Jacky Lam" <lamshuyin(a)gmail.com> wrote: > > Hi, > > Is there any generic way to get the physical address of memory > (first page) allocated by vmalloc()? PFN_PHYS( vmalloc_to_pfn( address )) -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com

1 0

Getting physical address of memory allocated by vmalloc()
by Jacky Lam Oct. 21, 2011

Oct. 21, 2011

Hi, Is there any generic way to get the physical address of memory (first page) allocated by vmalloc()? Thanks a lot. Jacky

1 0

How can I test if a physical address is already mapped or not.
by StephanT Oct. 20, 2011

Oct. 20, 2011

Hi all, In a kernel module is there a way to test if an address range has been already mapped by the kernel or not. Ex: (on a PC with the latest kernel) - an access to physical 0xC0000000 will return the value at this address - an access to physical 0x00100000 will have the kernel kill the module/application using the module. Dmesg: BUG: unable to handle kernel paging request at 00100000. How can I test this condition before dereferencing the address. Thanks, Stephan.

6 19

Getting 'bad file number' error writing to device driver
by Philip Anil-QBW348 Oct. 20, 2011

Oct. 20, 2011

I am trying to write to mydriver but get a 'Bad file number' error. int fd = open("/dev/mydriver",O_RDWR); this opens successfully as fd is not -1. ssize_t bytesToWrite = strlen(buf); value is: bytesToWrite 28 ssize_t bytesWritten = write(fd,buf,bytesToWrite); value is: bytesWritten -1 __android_log_print(ANDROID_LOG_INFO,__FILE__,"ANIL strerror(errno) %s", strerror(errno)); value is: strerror(errno) Bad file number Any help appreciated. Anil

3 8

mmap local APIC address
by Vaibhav Jain Oct. 19, 2011

Oct. 19, 2011

Hi, I am trying to map local APIC on an intel system (physical address 0xfee00000) in a user level program using mmap but my mmap is failing saying "Bad file descriptor". I am not sure if this problem is related to apic or mmap. I am running the program as root. Please help me figure this out. Thanks Vaibhav Jain

3 4

print contents of runqueue
by kashish bhatia Oct. 19, 2011

Oct. 19, 2011

Hi, I want to print contents of runqueue of my current processor. I got the pointer to current task_struct. To get runqueue, I called task_rq(). When compiled the module, it gave an error. Actually struct runqueue and task_rq() is not in any header file. It is present in kernel/sched.c Is there any way to access this structure without making changes to kernel . -- Regards, Kashish

1 0

Heap memory is not re-claiming.
by V.Ravikumar Oct. 18, 2011

Oct. 18, 2011

Hello all, I've a daemon process and I'm allocating heap memory** for big character buffers using malloc/free. Each can take 5MB. Though I freed/deleted memory allocated for the buffers, the increased memory during the allocation time is not re-claiming back.This I observed using *top* command. I'm sure I do not have any other memory leaks. I debugged the code line by line and observing memory usage using *top* command. During allocation time, *top* command showed that 30 MB increase in Virtual & Resident memory. Upon execution of delete/free statement on the buffers the raised memory was not re-claimed. On subsequent execution of the same code no extra memory was allocated even though new/malloc statements called on the buffers.What is kernel mechanism here. Is this due to some page cache re-mapping If this due to page cache then the memory should always constant trough out process life. During long run the memory slowly increasing. This should not happen. Could some body provide any insights into this.. Regards, Ravi

6 10

Linux System Calls vs writing device drivers
by Ashok Sharma Oct. 17, 2011

Oct. 17, 2011

Hello, I am interested in writing Linux device drivers (DD) and have knowledge of OS concepts, Linux OS design and System Calls. What is the path to writing DD and please give some references/links. Thank you and regards Ashok

3 3

Question about USB gadget driver usage
by Mikhail Boiko Oct. 17, 2011

Oct. 17, 2011

Hi We have linux-2.6.35 based device. Device has removable SD-card, which by certain condition is shared to PC vis USB connection using g_file_storage driver. Everything if fine, but when I manualy eject sd-card from cardholder, on my linux host machine, sd-card partition is still being mounted. In sources, there is a note, that if pass 'removable' parametr to g_file_storage module, locations specified by 'file' argument could be unmounted from sysfs by writing zero string to 'file'. But when try to do so, removal attempt is rejected in drivers/usb/gadget/storage_common.c:fsg_store_file() by first if-condition. 755 if (curlun->prevent_medium_removal && fsg_lun_is_open(curlun)) { 756 printk("eject attempt prevented\n"); 757 return -EBUSY; /* "Door is locked" */ 758 } As far as I understand, my host-pc blocks driver to eject certain LUN. Here is my parametrs to insert module insmod /lib/modules/g_file_storage.ko stall=0 removable=1 file=/dev/mmcblk0p4,/dev/mmcblk1p1 ro=0,0 where /dev/mmcblk0p4 is device internal memory (chip is soldered to pcb, so it can not be ejected) and /dev/mmcblk1p1 is removable sd-card Is there any way to perform `force eject` for one of my LUNs ? Thank you

1 0