- kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Why the PF_SUPERPRIV flag is cleared?
by Parmenides Sept. 8, 2011

Sept. 8, 2011

Hi, When forking a child process, the copy_process() function will by default clear the PF_SUPERPRIV flag, which indicates whether a process use superuser privileges. That means a superuser process will create a child process does not has superuser privileges. I think the child process of a superuser process should also be a superuser one, while the child process of a normal process by default should also be a normal one (except that the setuid bit of the child executable is turn on). In both cases it is not necessary that the PF_SUPERPRIV flag to be cleared. So, I wonder why the PF_SUPERPRIV flag is cleared by defult.

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Paging of Kernel Memory
by Vijay Chauhan Sept. 8, 2011

Sept. 8, 2011

Hi, i was going through the Linux Kernel Development book. It mention the following: "Additionally, kernel memory is not pageable.Therefore, every byte of memory you consume is one less byte of available physical memory." What is the meaning of 'Kernel memory is not pageable'? Anyone can give details would help me in understanding. Thanks, Vijay

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Doubt fork system call
by rohan puri Sept. 8, 2011

Sept. 8, 2011

Every time a fork() is callled in any user-space code, it internally invokes the clone() sys call, But if we linux kernel source code there is a system call by name fork(). So, what i really want to know is that, is there any case in which this syscall is getting called, or this code is deprecated. Regards, Rohan

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Invitation to connect on LinkedIn
by Anil Unnikrishnan via LinkedIn Sept. 8, 2011

Sept. 8, 2011

LinkedIn ------------ Anil Unnikrishnan requested to add you as a connection on LinkedIn: ------------------------------------------ Deepak, I'd like to add you to my professional network on LinkedIn. - Anil Accept invitation from Anil Unnikrishnan http://www.linkedin.com/e/8z2206-gsb6oul9-1a/L90NvsYL3GREvJdnM0f-HnfkWNbSD_… View invitation from Anil Unnikrishnan http://www.linkedin.com/e/8z2206-gsb6oul9-1a/L90NvsYL3GREvJdnM0f-HnfkWNbSD_… -- (c) 2011, LinkedIn Corporation

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How to identify the SD card in Linux.
by varun Yadav Sept. 7, 2011

Sept. 7, 2011

Hi, I want to identify SD card in Linux, like if we connect a usb mass storage device and SD card then how we can identify the SD card. Is usb driver sending some information regarding device type, class or sub class to user spaceby which i can identify that connected device is sd card? Regards, Varun

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Re: project on linux kernel
by Mulyadi Santosa Sept. 6, 2011

Sept. 6, 2011

On Tue, Sep 6, 2011 at 17:08, sugnan prabhu <sugnan.prabhu(a)gmail.com> wrote: >i am very much interested work on networking sub system, can you >please give me a project... I am not really into networking stuffs these days, so maybe folks here could help....folks? -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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freeze_bdev
by Mike Gibson Sept. 6, 2011

Sept. 6, 2011

Which filesystems are supported by freeze_bdev? The man page for fsfreeze shows Ext3/4, ReiserFS, JFS, and XFS. Is this correct? Mike Gibson

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analysis of kernel panic logs.
by sandeep kumar Sept. 6, 2011

Sept. 6, 2011

Hi, im working on android, kernel version 2.6.35.11 I got these logs showing kernel panic and the target is rebooting. >From the logs i understood in init process something is causing kernel panic. <3>[ 85.235589] init: [boot time] processing action 0x4c5e8 (property:init.svc.samsungani=stopped) <3>[ 85.236565] init: [boot time] processing action 0x4ef20 (property:init.svc.samsungani=stopped) <0>[ 85.236840] Kernel panic - not syncing: Attempted to kill init! <4>[ 85.236932] [<c01076b8>] (unwind_backtrace+0x0/0x164) from [<c072436c>] (panic+0x6c/0xec) <4>[ 85.237023] [<c072436c>] (panic+0x6c/0xec) from [<c01a931c>] (do_exit+0x70/0x6a0) <4>[ 85.237115] [<c01a931c>] (do_exit+0x70/0x6a0) from [<c01a99dc>] (do_group_exit+0x90/0xc0) <4>[ 85.237176] [<c01a99dc>] (do_group_exit+0x90/0xc0) from [<c01b8fc4>] (get_signal_to_deliver+0x3e0/0x424) <4>[ 85.237267] [<c01b8fc4>] (get_signal_to_deliver+0x3e0/0x424) from [<c01039d8>] (do_signal+0x68/0x640) <4>[ 85.237359] [<c01039d8>] (do_signal+0x68/0x640) from [<c0103fc8>] (do_notify_resume+0x18/0x38) <4>[ 85.237450] [<c0103fc8>] (do_notify_resume+0x18/0x38) from [<c0100bd0>] (work_pending+0x1c/0x20) <0>[ 85.237542] Rebooting in 5 seconds.. <2>[ 85.237572] CPU0: stopping <4>[ 85.237603] [<c01076b8>] (unwind_backtrace+0x0/0x164) from [<c0100338>] (do_IPI+0xd8/0x154) <4>[ 85.237695] [<c0100338>] (do_IPI+0xd8/0x154) from [<c0728188>] (__irq_usr+0x48/0xe0) <4>[ 85.237756] Exception stack(0xdc18dfb0 to 0xdc18dff8) <4>[ 85.237817] dfa0: 00000000 0000007c 00000000 4097b240 <4>[ 85.237878] dfc0: 45957cfe 4ba95bd8 4fc24a48 000000f4 80118200 ffffe9f4 00000000 801a6374 <4>[ 85.237939] dfe0: 000000f4 4fc249f8 8011d0a8 8011bf18 20000010 ffffffff But how to interpret the Exception stack, dfa0 etc., to narrow down what exactly caused the panic. And in similer cases when oops happens also we will get the register dump, i know how to interpret PC, but what about the rest of the registers. how they are useful in analysing the situation. -- With regards, Sandeep Kumar Anantapalli,

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How to identify Connected USB Storage device (Harddisk, flash Memory or SSD)
by mani Sept. 6, 2011

Sept. 6, 2011

Hi all, Is there any way to find out the type of the connected USB disk (Hard disk/SDD)? AFAIK there is a significant performance difference in Harddisk/SDD devices. Previously i though that the rotational flag in the sysfs will distinguish them but it is same for both the types #cat /sys/block/sda/queue/rotational 1 for both flash & HDD Is there any way to distinguish the USB Harddisk or SDD drives ? Thanks & Regards, Manish

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Regarding threaded irq and normal irq
by sandeep kumar Sept. 6, 2011

Sept. 6, 2011

HI all, I want to know whether threaded_irq will be in interrupt context or process context. I heard they replace workqueues. But i dont know which context they will be running in. Any furthur references where i get more info.. -- With regards, Sandeep Kumar Anantapalli,

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