May 2015 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

SynProxy can not return syn ack packets with asymmetric dual bridge topology
by Niyazi Sırt May 26, 2015

May 26, 2015

Hello all, I have a asymmetric dual bridge topology as shown below when i connect from 172.16.11.5 and 172.16.10.6 with ssh but i can not connect because of SynProxy. ------- | | ---o--- 172.16.11.5 | | -----o----- 172.16.11.6 | | | | default gw 1.1.1.1 | | 1.1.1.2/30 --o----o--- 2.2.2.2/30 | | | | | | (enp10s0f0) ----o----o----- | | | XXX | | | | br1 br0 | synproxy | | ----o----o----- | | | | | | 1.1.1.1/30 --o----o--- 2.2.2.1/30 | | | | default gw 2.2.2.2 | | -----o----- 172.16.10.1 | | ---o--- 172.16.10.6 | | ------- On all machines between 172.16.11.5 and 172.16.10.6 "rp filtering" is off and "ip forwarding" is on. There is a machine at the middle of topology which is called "XXX" machine. XXX has two bridges and a SynProxy. When SynProxy is turned OFF on XXX, I can ping from 172.16.11.5 to 172.16.10.6 and icmp packets follow this path: br1->172.16.10.1->172.16.10.6->172.16.10.1->br0. In addition, I can access from 172.16.11.5 to 172.16.10.6 with ssh. So the TCP traffic works as I expect. However, when SynProxy is turned ON on XXX, I can ping from 172.16.11.5 to 172.16.10.6 and icmp packets follow the same path. But I can not access from 172.16.11.5 to 172.16.10.6 using ssh. This is because synproxy can not send syn ack replies through br1 iface. If I add a route for synack packets on XXX, i can connect from 172.16.11.5 to 172.16.10.6 with ssh. route add 172.16.11.5 dev enp10s0f0 But this is not acceptable because 172.16.11.0 network is cloud. So i could not add route all cloud network to route table and could not add mac address to arp table. How can I connect from 172.16.11.5 to the 172.16.10.6 machine using ssh when SynProxy is turned ON on XXX? oris It possible? Thanks in advance, Niyazi

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How to install a older version kernel on new OS?
by Gao Peng May 22, 2015

May 22, 2015

I am using fedora 21,and kernel version is 3.17 but I compile a 2.6.32 kernel and install it,when I reboot I got error :"too old kernel",how Can I install a rather older kernel on a new system,is there some way fix it?

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when I subscribe linux-kernel mailing list , There is not any resposes! Why?
by sizel May 20, 2015

May 20, 2015

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memory addressing
by 慕冬亮 May 20, 2015

May 20, 2015

In Understanding the Linux kernel book, it says that linux kernel of x86 uses the segmentation and paging unit to transform logistic address to physical address! Up to now , kernel has gone to linux kernel 4.0 , does the segmentation exist in the x86? Is it only using the paging ? And in x86_64?

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device returned IRQ_WAKE_THREAD but no thread function avable error
by Chan Kim May 20, 2015

May 20, 2015

In the smsc911x Ethernet chip driver, I'm changing the FIFO write and read to DMA write and read. By the way, this driver uses loopback test during initialization using a simple test packet. I registered the DMA controller irq using request_irq(irq, handler, flags, name, dev) which calls request_threaded_irq(irq, handler, NULL, flags, name, dev). The process goes into sleep using wait_event_interruptible() after DMA command and I've seen the ISR handler is called by the DMA completion, and during the ISR, wake_up_interruptible() is called to wake up the process. But when the program runs I get this error message below during the first interrupt processing. "IRQ 2 device ald_dmac returned IRQ_WAKE_THREAD but no thread function available" I don't know why ald_dmac returned IRQ_WAKE_THREAD (because my interrupt handler only returns IRQ_HANDLED), and I have a feeling that in this case (processing going to sleep and woken up by the ISR), I should use some other method to register my interrupt. Can anybody give me some advice? Thanks a lot in advance. Chan Kim

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A flow path for ethernet kernel driver
by Airton Ishimori May 19, 2015

May 19, 2015

Hello, everybody, I'm trying to develop a new Ethernet driver (Realtek) for Linux kernel 4.0.2. [ 3.612938] r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded As part of my studies, I'm trying to trace the path for functions defined in drivers/net/ethernet/realtek/r8169.c, net/core/dev.c and net/core/dev_ioctl.c. I'm using "printks" for this purpose. For instance, something like: printk("TEST: __dev_set_promiscuity\n"); However, I'm not getting what's going on. I can set/unset the promiscuity behaviour via ifconfig command. [ 131.330091] device eth0 entered promiscuous mode [ 170.619086] device eth0 left promiscuous mode By looking at the dmesg output above, I thought the function that deals with promiscuity was __dev_set_promiscuity() defined in net/core/dev.c, because this function calls a function to print the message above: pr_info("device %s %s promiscuous mode\n", dev->name, dev->flags & IFF_PROMISC ? "entered" : "left"); But, when I tried to look for my printk message with dmesg after compiling and running the kernel, I couldn't find it. $ cd linux-4.0.2/ $ make net && make modules $ sudo make modules_install && sudo make install Can somebody help me to understand what's happening? Thanks in advance, *--*Airton Ishimori

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Question about struct block_device
by Rock Lee May 19, 2015

May 19, 2015

Hello: In struct block_device, there are two counters, one is bd_openers, and the other is bd_part_count. Why do there need those two counters? Can anybody give me some hint? -- Rock Lee

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Re: Addning new protocol and new driver on Linux
by Daniel. May 18, 2015

May 18, 2015

A new topic to the list :) - Write netlink api for access with iproute2 Cheers, 2015-05-18 17:21 GMT-03:00 Daniel. <danielhilst(a)gmail.com>: > Hi all! > > I have a driver for nordic nRF24L01+ module: > http://www.nordicsemi.com/eng/Products/2.4GHz-RF/nRF24L01P > > I'm looking for a requirements list of what I need to do. For now I have > this topics > > - Write driver using kernel NAPI (I already have a driver working with > cdev API) > - Write new protocol and export to userspace as a new socket type (no > ideia on this) > > As example I'm using the linux socketCan, I want to do like they did, but > with nRF24L01+. I have no ideia how this two topics touch one each other... > Any documentation, simple examples, tutorials, guide lines, articles or irc > chat on subject is welcome, I look on LDD3, but its outdated, I'm using > kernel 3.0 for development, > > As first version requeriment I want to send frames (32 bytes fixed) with > sendto() and receive (32 bytes fixed too) with recvfrom()... Messages > should be enqueued while sending, the driver need to iterate over a > circular list of remote nodes, exchaning frames and delivering the received > to userspace... > > Something like: > > for (;;) { > node *n = get_next_node(); > send_frames_to(n); // <- send enqueed frames, unblocking sendto() caller > receive_frames_from(n); // <- deliver received frames to recvfrom() > caller > } > > Thanks in advance! > Cheers > > -- > *"Do or do not. There is no try"* > *Yoda Master* > -- *"Do or do not. There is no try"* *Yoda Master*

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Addning new protocol and new driver on Linux
by Daniel. May 18, 2015

May 18, 2015

Hi all! I have a driver for nordic nRF24L01+ module: http://www.nordicsemi.com/eng/Products/2.4GHz-RF/nRF24L01P I'm looking for a requirements list of what I need to do. For now I have this topics - Write driver using kernel NAPI (I already have a driver working with cdev API) - Write new protocol and export to userspace as a new socket type (no ideia on this) As example I'm using the linux socketCan, I want to do like they did, but with nRF24L01+. I have no ideia how this two topics touch one each other... Any documentation, simple examples, tutorials, guide lines, articles or irc chat on subject is welcome, I look on LDD3, but its outdated, I'm using kernel 3.0 for development, As first version requeriment I want to send frames (32 bytes fixed) with sendto() and receive (32 bytes fixed too) with recvfrom()... Messages should be enqueued while sending, the driver need to iterate over a circular list of remote nodes, exchaning frames and delivering the received to userspace... Something like: for (;;) { node *n = get_next_node(); send_frames_to(n); // <- send enqueed frames, unblocking sendto() caller receive_frames_from(n); // <- deliver received frames to recvfrom() caller } Thanks in advance! Cheers -- *"Do or do not. There is no try"* *Yoda Master*

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Linux 14.04 stuck at "Loading initial RAM disk"
by Ramesh May 18, 2015

May 18, 2015

Hi All, I have linux 14.04 with 64-bit kernel and recently I installed 32 bit kernel in my machine. After installation complete I restarted machine to login to new 32 bit kernel. But when I try to logging in to the newly installed 32 bit kernel system get stuck in "Loading initial RAM disk" Please someone help me Thanks in advance... -- Regards, Ramesh

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