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

How to know which programming model is used on may Linux machine
by Pritam Bankar July 25, 2012

July 25, 2012

Hi, AFAIK there are three programming model that can be chosen on 64 bit environment. These models are LP64, ILP64, LLP64 Question 1) But how can I know which model is used on my system ? Question 2) Does long long data type is limited for LLP64 type model ? (My system is redhat 6.2 64bit) Thanks Pritam Bankar

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RE: How to know which programming model is used on may Linux
by Rajat Sharma July 25, 2012

July 25, 2012

machine MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Just compile the code with kbuild and print sizeof? -- Rajat From: Pritam Bankar Sent: 25-07-2012 16:34 To: kernelnewbies Subject: How to know which programming model is used on may Linux machine Hi, AFAIK there are three programming model that can be chosen on 64 bit environment. These models are LP64, ILP64, LLP64 Question 1) But how can I know which model is used on my system ? Question 2) Does long long data type is limited for LLP64 type model ? (My system is redhat 6.2 64bit) Thanks Pritam Bankar _______________________________________________ Kernelnewbies mailing list Kernelnewbies(a)kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

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Dm-Raid1 Issue
by Gaurav Mahajan July 25, 2012

July 25, 2012

Hi, I want to run Dm-raid1 or dm-mirror in degraded mode. So say I have 2 Disks and I create a mirror device over that. Create EXT4 over the new device, mounted it and started a huge number of IO using dd on that device. Now while the IO are going on, I failed the 'Default' Mirror in the mirror set. Then ideally the IO operation should not break. All the IO should go to other mirror. But it is not happening. Either my dd command hangs till the default device comes back or it returns an IO error and breaks the IO operations on disk. Is this is known behavior ? Or I am missing something in configuration ? I am using Kernel 2.6.32. Mirror target's version is 1.12.0 Please help ! Thanks, Gaurav

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suse 11 kernel panic
by tingwei liu July 25, 2012

July 25, 2012

Suse 11 SP1 kernel panic。 I can't debug it without debuginfo. Who can give me a link of sels 2.6.32.12-0.7.default.debug or give some advise. Thanks for any reply! kernel: [3077010.856280] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 kernel: [3077010.856291] IP: [<ffffffff81046958>] find_busiest_group+0x348/0x8b0 kernel: [3077010.856302] PGD a46ac067 PUD 8c828067 PMD 0 kernel: [3077010.856307] Oops: 0000 [#1] SMP kernel: [3077010.856312] last sysfs file: /sys/devices/system/cpu/cpu23/cache/index2/shared_cpu_map kernel: [3077010.856318] CPU 19 kernel: [3077010.856320] Modules linked in: bluetooth rfkill af_packet drbd iptable_filter ip_tables x_tables nfs lockd fscache nfs_acl auth_rpcgss sunrpc ipv6 cpufreq_conservative cpufreq_userspace cpufreq_powersave pcc_cpufreq fuse loop dm_mod tpm_tis tpm tpm_bios bnx2 e1000e iTCO_wdt rtc_cmos serio_raw rtc_core hpilo pcspkr iTCO_vendor_support rtc_lib hpwdt joydev power_meter button container usbhid hid uhci_hcd ehci_hcd usbcore edd ext3 mbcache jbd fan processor hpsa cciss scsi_mod thermal thermal_sys hwmon kernel: [3077010.856370] Supported: Yes kernel: [3077010.856375] Pid: 5762, comm: program_t Not tainted 2.6.32.12-0.7-default #1 ProLiant DL380 G7 kernel: [3077010.856379] RIP: 0010:[<ffffffff81046958>] [<ffffffff81046958>] find_busiest_group+0x348/0x8b0 kernel: [3077010.856387] RSP: 0018:ffff880112f59ab8 EFLAGS: 00010006 kernel: [3077010.856391] RAX: 00000000009da550 RBX: ffff880123c0ebc0 RCX: 0000000000000000 kernel: [3077010.856395] RDX: 0000000100000000 RSI: 0000000000000020 RDI: 0000000000000000 kernel: [3077010.856399] RBP: ffff880112f59c28 R08: 0000000000000020 R09: ffff880123c0ebd0 kernel: [3077010.856404] R10: 0000000000000000 R11: 0000000100000000 R12: 0000000000000000 kernel: [3077010.856408] R13: 0000000100000000 R14: 0000000000000000 R15: ffff880123c0ebd0 kernel: [3077010.856413] FS: 00007fc35fbac710(0000) GS:ffff880123d20000(0000) knlGS:0000000000000000 kernel: [3077010.856417] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 kernel: [3077010.856421] CR2: 0000000000000008 CR3: 0000000018124000 CR4: 00000000000006e0 kernel: [3077010.856426] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 kernel: [3077010.856430] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 kernel: [3077010.856434] Process program_t (pid: 5762, threadinfo ffff880012f58000, task ffff88000db421c0) kernel: [3077010.856438] Stack: kernel: [3077010.856441] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 kernel: [3077010.856445] <0> 0000000000000000 0000000000000000 0000000000000000 0000000000000000 kernel: [3077010.856450] <0> 0000000000000000 0000000000000000 0000000000000000 0000000000000000 kernel: [3077010.856457] Call Trace: kernel: [3077010.856467] Inexact backtrace: kernel: [3077010.856468] kernel: [3077010.856472] Code: 74 10 48 8b 75 10 44 8b 2e 45 85 ed 0f 84 a3 02 00 00 48 8b 95 00 ff ff ff 44 8b a5 f8 fe ff ff 48 8b 45 a8 48 01 85 20 ff ff ff <8b> 42 08 48 01 85 28 ff ff ff 45 85 e4 74 14 48 8b 45 c0 ba 01

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using arc4 algorithm of linux kernel crypto subsystem
by Arif Hossain July 24, 2012

July 24, 2012

Hi, I'm trying to use the "arc4" algorithm to to encrypt a arbitrary data stream from a module. But i'm a little clueless about how should i approach it.the implementation is in <crypto/arc4.c> $find . -type f -name '*.[ch]' -exec grep 'EXPORT_SYMBOL' {} \; | grep 'rc4' returned nothing. So i guess there is no external interface to static void arc4_crypt(struct crypto_tfm *tfm, u8 *out, const u8 *in). The register function is defined as static int __init arc4_init(void) { return crypto_register_alg(&arc4_alg); } And there is a static instance of struct crypto_alg. By these hints, I've come to conclusion that, I need a higher level interface to access this algorithm. Only function which seems relevant in my case is : EXPORT_SYMBOL_GPL(crypto_alloc_tfm); from <crypto/api.c> : void *crypto_alloc_tfm(const char *alg_name, const struct crypto_type *frontend, u32 type, u32 mask) it returns void * which is my first concern. And also from <crypt/api.c> crypto_alloc_tfm() will first attempt to locate an already loaded algorithm. If that fails and the kernel supports dynamically loadable modules, it will then attempt to load a module of the same name or alias. If that fails it will send a query to any loaded crypto manager to construct an algorithm on the fly. A refcount is grabbed on the algorithm which is then associated with the new transform. The returned transform is of a non-determinate type. Most people should use one of the more specific allocation functions such as crypto_alloc_blkcipher. But no specific crypto_alloc_* i could find which will provide arc4 algorithm. Second concern: struct crypto_type in <include/crypto/algapi.h> is looking horrendous to instantiate by hand. And lastly if get a tfm instance, how i use it to do actual encryption?

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What is difference between declaring long and long int
by Pritam Bankar July 24, 2012

July 24, 2012

Hi, long long x; long long int y; Anybody please tell me, is there any difference between declaring variable with long long and long long int ? Does both declaration mean same thing ? Thanks, Pritam Bankar

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Hash table implementation
by Arif Hossain July 24, 2012

July 24, 2012

Hi, This commit shows that jenkins hash function(http://en.wikipedia.org/wiki/Jenkins_hash_function) is implemented in kernel : commit 60d509c823cca21e77d537bd356785f7cfe8f0d1 Author: Jozsef Kadlecsik <kadlec(a)blackhole.kfki.hu> Date: Fri Dec 3 02:39:01 2010 +0000 The new jhash implementation <snip> I could not find any good documentation describing how to use it. Only thing i could do is to read codes which uses it, like /net/netfilter/xt_NFQUEUE.c. I have got some idea about how it works. But a good documentation would have been better. Like this one describing linux's implementation of doubly linked list : http://isis.poly.edu/kulesh/stuff/src/klist/ It describes how i can use this even in user land code. If i could do this for jhash then the understanding would have been better. Cheers.

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How can I change cr0 register in redhat system
by Fan Yang July 24, 2012

July 24, 2012

hi all: when I change the cr0 register I get a "Segmentation fault (core dumped)". my code is : .data .text .global _start _start: movl %eax, %cr0 this code can work well in ubuntu system when I use root to run it. So what can I do to work it in redhat system? thanks

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Re: Hash table implementation
by Arif July 23, 2012

July 23, 2012

On Jul 23, 2012, at 11:31 PM, Hans Schillstrom wrote: >> Subject: Hash table implementation >> >> Hi, >> >> This commit shows that jenkins hash >> function(http://en.wikipedia.org/wiki/Jenkins_hash_function) is >> implemented in kernel : >> >> commit 60d509c823cca21e77d537bd356785f7cfe8f0d1 >> Author: Jozsef Kadlecsik <kadlec(a)blackhole.kfki.hu> >> Date: Fri Dec 3 02:39:01 2010 +0000 >> >> The new jhash implementation >> <snip> >> >> I could not find any good documentation describing how to use it. >> Only >> thing i could do is to read codes which uses it, like > > Have a look in the include file it self linux-3.5.0/include/linux/ > jhash.h > every function is well documented there. > Thanks for the reply. I have looked through it. I guess the file serves well. I should pay attentions to comments more. Its just the guys i develop with, they put horrible comments, and i developed a habit of overlooking them. > /Hans > > -- > To unsubscribe from this list: send the line "unsubscribe netfilter- > devel" in > the body of a message to majordomo(a)vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html

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Re: How can I change cr0 register in redhat system
by Fan Yang July 23, 2012

July 23, 2012

2012/7/23 Ram Tummala <venkatram867(a)gmail.com> > On Jul 23, 2012, at 9:32 AM, Fan Yang <lljyangfan(a)gmail.com> wrote: > > > hi all: > > when I change the cr0 register I get a "Segmentation fault (core > dumped)". > > my code is : > > > > > > .data > > .text > > .global _start > > _start: > > movl %eax, %cr0 > > > > this code can work well in ubuntu system when I use root to run > it. So what can I do to work it in redhat system? > > Changing a control register is a privileged operation. You can't do it > from the user space. You can only do it from ring 0. > > Venkatram Tummala > > > > thanks > > > > _______________________________________________ > > Kernelnewbies mailing list > > Kernelnewbies(a)kernelnewbies.org > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > May be I can work it by adding a new syscall in the kernel, right?

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