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Bio flags
by Praveen Kumar July 5, 2016

July 5, 2016

Hi, I am porting some of file system related code from 3.0.101 kernel to 4.4.13 kernel and found that the number of bio flags have been reduced from 13 to 8 and some of the which been removed are : BIO_UPTODATE BIO_RW_BLOCK BIO_EOF BIO_EOPNOTSUPP ... I was unable to find much in the documentation sections regarding the flags. Can someone please help providing inputs or pointers over this change. Thank you for your help. Regards, ~Praveen.

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Bios , Mbr, Grub
by Gnoleba GNOGBO July 5, 2016

July 5, 2016

Hi ! I had read a lot of book and link about initialization of the boot starting of linux. I read that , after the post by the bios the mbr is loaded in memory which routine load this sector ? In this sector of 512 bytes we have 440 bytes for a routine what is the function of this routine ? When this routine is executed ? The 2 bytes with 0xAA55 what is its function ? Who load it in memory ? And the all book i had read said the mbr load the loader grub How ? And the grub launch the kernel, ok . How this grub is load ? By which programm ? So, i would like that someone give me the names of routines, the order of their launching and which load or execute what until the grub exécution ? Thank you for your help. Greg i am waiting a lot from you ! Best regards Gnoleba GNOGBO

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IOMMU
by Max Ruttenberg July 4, 2016

July 4, 2016

What does code in drivers/iommu do? What is it responsible for and how would it relate to a custom kernel module say for a PCI driver? -- Max Ruttenberg, Member of the Technical Staff Emu *Technology* 1400 E Angela Blvd, Unit 101 South Bend, IN 46617

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spi can't read more than 64 bytes
by Moti Cohen July 3, 2016

July 3, 2016

Hi all, I'm trying to write a kernel device driver for a Freescale imx6 processor based board. This driver is using spi to communicate with a radio module (using linux spi.c). I managed to wr/rd from the module, however once I'm trying to read more than 64 bytes I'm getting coruppted data. here are some details: The SPI reading process goes as follows: 1. Interrupt function is invoked from SPI device via dedicated GPIO line. 2. The interrupt function performs asynchronous SPI read in the following order: 2.1 radio_trx_end_callback is called, as it is the registered call back function. 2.2 radio_trx_end_callback calls hal_frame_read function which prepares spi_message and spi_transfer structures and fill them with relevant data: spi_device , data tx, transfer len , complete handler , … 3. The read itself is done by calling to function spi_async 4. The completion handler function is called and prints the read message, but trying to read more than 64 bytes in one transaction causes the read data to be corrupted. Any idea why am I seeing this behavior ? Is there (in Linux) any definition for the size to be read via the SPI ? The relevant variables and functions can be seen below: Thanks in advance for helping.. __________________________ uint8_t rx_buf[200]; uint8_t reg[200] = {HAL_TRX_CMD_FR, 0xff, 0xff}; struct spi_transfer transfer; struct spi_message spi_msg; // interrupt function //----------------------------------------------------------------------------------------------------------------------- static irq_handler_t radio_trx_end_callback(unsigned int irq, void *dev_id, struct pt_regs *regs) { hal_frame_read(irq, dev_id); return (irq_handler_t) IRQ_HANDLED; // Announce that the IRQ has been handled correctly } //read function //----------------------------------------------------------------------------------------------------------------------- void hal_frame_read(unsigned int irq, void *dev_id) { int status; spi_device->irq = irq; spi_message_init(&spi_msg); spi_msg.spi = spi_device; spi_msg.complete = rf_rx_completion_handler; spi_msg.context = NULL; memset((uint8_t*)&transfer, 0, sizeof(transfer)); memset(rx_buf, 0xFF, sizeof(rx_buf)); memset(reg, 0xFF, sizeof(reg)); reg[0] = HAL_TRX_CMD_FR; transfer.tx_buf = reg; transfer.len =64; transfer.rx_buf = rx_buf; spi_message_add_tail(&transfer, &spi_msg); memset(rx_buf, 0x0, sizeof(rx_buf)); status = spi_async(spi_device, &spi_msg); return; } //read completion handler //----------------------------------------------------------------------------------------------------------------------- static void rf_rx_completion_handler(void *arg) { int ii; //print the received message printk("\npure message: rx_buf [1]-2=%02X\n ", rx_buf [1]-2); for (ii=0; ii< rx_buf [1]-2; ii++) printk("%02X ", rx_buf [2+ii]); printk("\nframe len=%X actual len=%X status=%i\n",spi_msg.frame_length, spi_msg.actual_length, spi_msg.status); send_up_rf_event_to_workque(TRX_END_EVENT); }

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Re: Replying to E-mails I did not receive
by Peter Senna Tschudin July 3, 2016

July 3, 2016

On Jul 3, 2016 17:10, <Valdis.Kletnieks(a)vt.edu> wrote: > > On Sun, 03 Jul 2016 13:10:42 +0200, Peter Senna Tschudin said: > > Hi! > > > > I tested a few patches sent to lists I'm not subscribed to. I want to > > reply to the thread with my "Tested-by: " and "Acked-by:", but I'm not > > sure what is the best way to do it. > > > > Is it enough to simply compose a new message with the original text as > > a reply to the correct message id? > > Why not just do a 'reply all' and let your mail software do the heavy lifting? > It's always worked for me.... Because I don't have the emails. I downloaded the patches from the mailing list web page...

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Replying to E-mails I did not receive
by Peter Senna Tschudin July 3, 2016

July 3, 2016

Hi! I tested a few patches sent to lists I'm not subscribed to. I want to reply to the thread with my "Tested-by: " and "Acked-by:", but I'm not sure what is the best way to do it. Is it enough to simply compose a new message with the original text as a reply to the correct message id? How you usually do that? Thank you! Peter -- Peter

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Kernel Version 4.6.3 - build error
by Michael McCann July 2, 2016

July 2, 2016

Has anyone seen this problem when building 4.6.3? Mike KB2GHZ * HOSTCC scripts/recordmcount HOSTCC scripts/sortextable HOSTCC scripts/asn1_compiler HOSTCC scripts/sign-filescripts/sign-file.c:25:30: fatal error: openssl/opensslv.h: No such file or directory #include <openssl/opensslv.h> ^compilation terminated.make[1]: *** [scripts/sign-file] Error 1make: *** [scripts] Error 2real 0m13.452suser 0m8.704ssys 0m5.631s*

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convension about type argument on _IO macro
by Colin Vidal July 2, 2016

July 2, 2016

Hi all, In LDDv3, chapter 6, on ioctl, macros IOCTQUANTIUM is defined with _IO(SCULL_MAGIC, 3). IOCT_* tells that a value (given directly as value through the argument) is set to the device. However, no type is given to this macro. It is not a big deal since this macro is just a helper to generate identifiers, but, I wonder if there is any convention telling that we should precise an argument only if it's a pointer ? Thanks - Colin

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no device creation by udev
by anno79＠mailbox.org July 1, 2016

July 1, 2016

I have written the following lines of code to get a char device working. ( lines with # indicate that I have tried versions of this code snippet without them) class_hello = class_create(THIS_MODULE, device_name); # class_hello->devnode = &hello_devnode; retval = alloc_chrdev_region( &dev_file, 0, 1, device_name ); cdev_init( &device, &file_ops ); # device.owner = THIS_MODULE; # kobject_set_name(&device.kobj, device_name); cdev_add( &device, MKDEV(dev_file, 0), 1 ) device = device_create( class_hello, NULL, MKDEV(dev_file, 0), NULL, device_name ); # kobj_device->devt = MKDEV(dev_file, 0); Make it open / close / read / write works fine - but look at that $ ls /sys/class/hello/hello power subsystem uevent The "dev" entry is missing - and udev does not react. Anybody knows what is else needed to make udev react?

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Init task 8192 byte alignment query.
by Shiva Shankar June 30, 2016

June 30, 2016

Hi I was going through arm vmlinux script file. and i found below statements /* * first, the init task union, aligned * to an 8192 byte boundary. */ INIT_TASK_DATA(THREAD_SIZE) #define INIT_TASK_DATA(align) \ . = ALIGN(align); \ *(.data..init_task) As i know we align data structures on a n byte boundary to save access time and for speed execution but i did not understand why do we need to align this particular data structure on a 8192 byte boundary. sometimes it will be on 1024 or 2048 byte boundary. Any inputs would be appreciated!!! Regards

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