June 2012 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Re: New kernel for Chipbox
by Sertac TULLUK June 7, 2012

June 7, 2012

How about 3.4.1 ? (2.6.32.XX is even enough for me) ----- Original Message ----- From: Harishkumar V To: Sertac TULLUK Cc: kernelnewbies(a)kernelnewbies.org Sent: Thursday, June 07, 2012 3:53 PM Subject: Re: New kernel for Chipbox To which kernel version, u going to port it ???

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How to understand super.c/descriptor_loc for ext2/ext3/ext4?
by Ryan Wang June 7, 2012

June 7, 2012

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Suggest good reads..!!!
by manty kuma June 7, 2012

June 7, 2012

Hi, TO enhance kernel level terminologies, different coding standards and styles of coding inside Linux kernel (or drivers that need to be written for Linux kernel)are there any good references. Kind of MUST reads for linux kernel programmers.? Rgds, Manty

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Fwd: How can I disable all USB devices?
by 夏业添 June 5, 2012

June 5, 2012

Thanks for reply! But it seems not suitable for my job. Sorry for that I didn't talk about my situation clearly. I was asked to only enable usb Network Interface Card, and disable all other usb devices(like keyboard, mouse, stick, etc.). I need a way to distinguish different usb devices and disable/enable them. If anyone has some idea, please tell me. 2012/6/5 <Ashish_Bunkar(a)dell.com>: > Hi > > You can just disable the USB support for your kernel by editing kernel parameters. > Just add "nousb" to you kernel parameters In "/etc/grub.conf" and your kernel should not support USB device thereafter. > Also when you would like to enable them again just remove "nousb" from kernel command line and all should work fine with that. > > Please let me know if that helped you. > > Ashish Bunkar > Linux Engineering > Dell | BDC > office +91-80-28078131, mobile +91-7259183696 > Ashish_Bunkar(a)dell.com > > > > -----Original Message----- > From: kernelnewbies-bounces(a)kernelnewbies.org [mailto:kernelnewbies-bounces@kernelnewbies.org] On Behalf Of ??? > Sent: Tuesday, June 05, 2012 8:48 AM > To: kernelnewbies > Subject: How can I disable all USB devices? > > Hi there, > > I want to disable all my USB devices (mouse, keyboard,... ) now, but hope to enable some certain device in the future. And I don't want to recompile kernel or disable usb module. > > I've searched on the Internet, and it seems that udev manage devices connecting to my computer. Can I use udev to disable all USB devices? > > Thanks! > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies(a)kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

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How can I disable all USB devices?
by 夏业添 June 5, 2012

June 5, 2012

Hi there, I want to disable all my USB devices (mouse, keyboard,... ) now, but hope to enable some certain device in the future. And I don't want to recompile kernel or disable usb module. I've searched on the Internet, and it seems that udev manage devices connecting to my computer. Can I use udev to disable all USB devices? Thanks!

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[RFC]confusions about 'struct' define
by harryxiyou June 4, 2012

June 4, 2012

Hi guys, When I read the linux/device.h file for some device driver usage, i find some confusions like following. $ head -60 device.h [...] struct device; struct device_private; struct device_driver; struct driver_private; struct module; struct class; struct subsys_private; struct bus_type; struct device_node; struct iommu_ops; struct bus_attribute { struct attribute attr; ssize_t (*show)(struct bus_type *bus, char *buf); ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count); }; [...] I have never seen struct define like "struct device; struct device_private; struct device_driver; [...] struct device_node; struct iommu_ops;" The common define is like this "struct a{ int a; int b; [...] }" Is this just struct declaration or some extension about gcc? Cloud anyone give me some explanations? Thanks in advance ;-) Note: my kernel version is 3.0 around. -- Thanks Harry Wei

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Driver for BlinkM i2c LED module
by Jan-Simon Möller June 3, 2012

June 3, 2012

Hi all! *drum roll* This is the first version of the blinkM i2c led driver. blinkM is an RGB led module which hooks up to an i2c bus. See http://thingm.com/products/blinkm . The protocol uses sequences of i2c commands to communicate with the tiny embedded controller. This driver implements the needed bits to make the blinkM work as LED device (accepting the triggers in sysfs) and also has a sysfs group for the more "advanced settings" exposed by the controller. Of course not all advanced options are implemented yet ;). Comments ? I'm also looking for the best place to fit this in. Staging ? drivers/led ? Have Phun! Best, Jan-Simon

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Issue in ioctl func call of character driver.
by KARTHIK SEKURU June 2, 2012

June 2, 2012

Hi, I am new to kernel device drivers. I wrote a simple character driver built statically having the fops as shown: *static const struct file_operations mfcfpga65_usb_fops = {* * .owner = THIS_MODULE,* * .open = mfcfpga65_usb_open,* * .read = mfcfpga65_usb_read,* * .unlocked_ioctl = mfcfpga65_usb_ioctl,* * .release = mfcfpga65_usb_close,* *};* All the driver registrations are done properly. I wrote a sample application to test these drivers implementing open,read and ioctl calls. open and read are working fine whereas ioctl is not behaving as expected. The application code is as shown: *int main()* *{* * printf("Enterred main function : \n");* * int fd=0,ret=0;* * char buff[80]="";* * * * fd=open("/dev/usbmod",O_RDONLY);* * if(fd<0) * * {* * printf("fd value is less than 0\n");* * }* * * * printf("fd :%d\n",fd);* * * * ret=read(fd,buff,10);* * buff[ret]='\0';* * * * printf("The commands passed are %d and %d\n",IOCTL_USB_READ,IOCTL_USB_OPEN );* * ret = ioctl(fd,IOCTL_USB_READ);* * ret = ioctl(fd,IOCTL_USB_OPEN); * * * * close(fd);* *}* The cmds in ioctl are defined in seperate header file which is included in driver as well as in the applicatin.That definations are as shown *#define MFCFPGA65_NUM 254* * * *#define IOCTL_USB_OPEN _IO(MFCFPGA65_NUM,0)* *#define IOCTL_USB_READ _IO(MFCFPGA65_NUM,1)* *#define IOCTL_USB_WRITE _IO(MFCFPGA65_NUM,2)* The IOCTL call in driver does nothing except printk in each switch case showing to which case statement it entered .This ioctls implementation in driver is as shown below: *static long mfcfpga65_usb_ioctl(struct inode *inode, struct file *file, unsigned int iocmd,* * unsigned long ioarg)* *{* * * * void __user *arg = (void __user *)ioarg;* * unsigned int* stream;* * unsigned int size;* * * * printk(KERN_INFO "In IOCTL function of USB character driver with cmd as %d : \n",iocmd);* * * * printk(KERN_INFO "The switch case cmds are %d %d %d\n",IOCTL_USB_OPEN,IOCTL_USB_READ,IOCTL_USB_WRITE);* * * * switch (iocmd) {* * * * case IOCTL_USB_OPEN:* * * * printk(KERN_INFO "In IOCTL case1 of USB character driver: \n");* * return 0;* * break;* * * * case IOCTL_USB_READ:* * * * printk(KERN_INFO "In IOCTL case2 of USB character driver: \n");* * return 0;* * break;* * * * case IOCTL_USB_WRITE:* * * * printk(KERN_INFO "In IOCTL case3 of USB character driver: \n");* * return 0;* * break;* * * * }* *}* >From application i made sure that i am passing proper cmd arguments.The control goes to the ioctl function call in driver but doesn't go to the proper switch cases. This is because the iocmd argument received in the ioctl implementation is getting corrupted i.e eventhough from application i am passing *IOCTL_USB_READ , **IOCTL_USB_OPEN *parameters,when i check them in ioctl function in drivers the values are changed and through printk in the ioctl i could see that the iocmd received in the function is 4096 value which doesn't match to IOCTL_USB_READ or IOCTL_USB_OPEN. Please let me know how can the command argument passes via ioctl call in application is modified/corrupted before it reaches the actual ioctl implementation in drivers. thanks, Karthik.

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Faking SD-Card insertion/removel
by sougata santra June 1, 2012

June 1, 2012

I am new to linux device-drivers. I am trying to fake add, remove sd cards while they are mounted. For systems where sd card controller is connected to PCI bus. I can use fakephp to remove the controller itself. Can similar thing be done with "mmc" bus_type. So that I can fake card addition and removal. The current version of fakephp does not use anything from pci-hotplug subsystem. Is something similar possible ?. Thank you in advance. Best regards, Sougata.

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Re: cache policy of arm mmu
by h.t.jacky＠gmail.com June 1, 2012

June 1, 2012

Hi Cunsuo, Thanks for you prompt reply. But I'm just wondering why the other policies(such as writethrough) are abandoned, does anyone know the architecture difference? Cheers, Jacky Sent from my HTC ----- Reply message ----- From: "Cunsuo Guo" <cunsuo.guo(a)gmail.com> To: "Jacky lin" <h.t.jacky(a)gmail.com> Cc: <kernelnewbies(a)kernelnewbies.org> Subject: cache policy of arm mmu Date: Tue, May 29, 2012 09:10 Hi Jacky， I think the information of printk has already tell us the reason. 2012/5/29 Jacky lin <h.t.jacky(a)gmail.com>: > Hi all, > > I found that the cache policy in after ARMv6 is always set as writeback mode > in mmu.c. > > static int __init early_cachepolicy(char *p) > { > ... > if (cpu_architecture() >= CPU_ARCH_ARMv6) { > printk(KERN_WARNING "Only cachepolicy=writeback supported on ARMv6 > and later\n"); > cachepolicy = CPOLICY_WRITEBACK; > } > ... > } > > Does anyone know why and provide some documents or links for that? > > Thanks so much! > > Cheers, > Jacky > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies(a)kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >

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