December 2012 - kernelnewbies@kernelnewbies.org

How do I know if I have ISA bus
by Woody Wu Dec. 24, 2012

Dec. 24, 2012

Hi, If my system has ISA bus and some ISA devices attched to it, can I confirm that by checking the existence of any file in /proc, /sys or /dev? Thanks. -- woody I can't go back to yesterday - because I was a different person then.

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Difference x86 and x86_64
by Shraddha Kamat Dec. 24, 2012

Dec. 24, 2012

I used x86 - bzImage to boot my machine and 'uname -a' shows this :- Linux phx4 3.7.1 #3 SMP Sun Dec 23 16:28:20 IST 2012 x86_64 x86_64 x86_64 GNU/Linux where I see x86_64 arch (and not x86_64) ??? What is the difference between arch/x86 and arch/x86_64 ? -- Shraddha

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Re: Linux Kernel: get_user_pages_fast
by Mulyadi Santosa Dec. 24, 2012

Dec. 24, 2012

On Sat, Dec 22, 2012 at 7:22 PM, Pablo Pessolani <ppessolani(a)hotmail.com> wrote: > Hi Mulyadi: > I have developed Minix3 IPC primitives under Linux. One of it > (sys_vcopy) allows to copy bytes from one process' user space to other > process' user space. > Those IPCs use spinlocks to synchronize and get_user_pages() to copy > bytes and/or pages from one process' address space to the other. All it > works fine and with acceptable performance. Now, I want to improve > performance using RCU and the "fast" version of get_user_pages(). hmmm....check process_vm_rw_pages() at http://lxr.linux.no/#linux+v3.7.1/mm/process_vm_access.c#L42 maybe that's what you need.... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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how to use git bisect on such seanario
by bill4carson Dec. 24, 2012

Dec. 24, 2012

Hi, list Usually, we use git bisect to identify which commit causes trouble, while how do I do when need to find out which commit solve problem? for example, it's know there is an bug since commit A, but I find out the newest version (commit B)is good, so one commit between commit A and B solve the problem, thanks -- 浮沉随浪只记今朝笑 --bill

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Why can not install kernel headers?
by mobile.parmenides Dec. 23, 2012

Dec. 23, 2012

I am reading an article about kernel header installtion, its links as follows: http://lxr.linux.no/#linux+v2.6.32/Documentation/make/headers_install.txt#L… Following a command given by the article: make headers_install ARCH=i386 INSTALL_HDR_PATH=/usr/include the kernel headers should be installed into '/usr/include'. However, when checking '/usr/include/linux' and '/usr/include/asm', I found actually these kernel headers have not installed (by checking timestamps). In fact, kernel headers have be installed into 'include' subdirectory of kernel top-level directory. Obviously, the 'INSTALL_HDR_PATH' parameter in the above command does not take effect. Is there any way to deal with the problem? If I have to use 'cp' to install headers by hand, the 'INSTALL_HDR_PATH' seems not to play its roles. -------------- mobile.parmenides

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EACESS when trying to open the file
by Niroj Pokhrel Dec. 22, 2012

Dec. 22, 2012

Hi, I have been trying to open a character device and getting the following error : open("/dev/mychardev", O_RDONLY) = -1 EACCES (Permission denied) What do I have to change my permission mode ?? Please help. Thanx in advance . -- Niroj Pokhrel Software Engineer, Samsung India Software Operations

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Re: EACESS when trying to open the file
by Niroj Pokhrel Dec. 22, 2012

Dec. 22, 2012

On Sat, Dec 22, 2012 at 9:49 PM, Adel Qodmani <mpcadel(a)gmail.com> wrote: > I am not sure, but try running your application as a root > > Adel, > > > On Sat, Dec 22, 2012 at 6:09 PM, Niroj Pokhrel <nirojpokhrel(a)gmail.com>wrote: > >> Hi, >> I have been trying to open a character device and getting the following >> error : >> open("/dev/mychardev", O_RDONLY) = -1 EACCES (Permission denied) >> What do I have to change my permission mode ?? >> Please help. Thanx in advance . >> >> -- >> Niroj Pokhrel >> Software Engineer, >> Samsung India Software Operations >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies(a)kernelnewbies.org >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> >> > Thank you Adel. It worked. -- Niroj Pokhrel Software Engineer, Samsung India Software Operations

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Fwd: Query on vfs interface
by Mulyadi Santosa Dec. 22, 2012

Dec. 22, 2012

sorry, forgot to cc to the list :) ---------- Forwarded message ---------- From: Mulyadi Santosa <mulyadi.santosa(a)gmail.com> Date: Sat, Dec 22, 2012 at 8:58 AM Subject: Re: Query on vfs interface To: Raghavendra G <raghavendra.g(a)stericsson.com> On Fri, Dec 21, 2012 at 1:34 PM, Raghavendra G <raghavendra.g(a)stericsson.com> wrote: > > Hello > > I am trying to log all the calls going to the VFS file system from the > application. > > > > For write calls I notice an anomaly. I introduced a log at the > vfs_write() function , I see it get’s logged twice for every write in the > log output. my best guess is: first write: updating file metadata, likely access time timestamp second write: updating the data itself.... to see whether it's true, re-mount the partition where the data stays with "noatime"..... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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Linux Kernel: get_user_pages_fast
by Pablo Pessolani Dec. 22, 2012

Dec. 22, 2012

Hi: I want to add a new a new kernel function: get_user_pages_fast2() based on get_user_pages_fast() for other process than "current". Does anybody has any consideration or warning to tell me. Thanks in advance. Pablo Pessolani Argentina.

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gcc 2.95.3 compile failure
by horse_rivers Dec. 21, 2012

Dec. 21, 2012

hi: I am trying to compile gcc2.95.3 ,after I patch source code , and configure , make fail with this :gcc-2.95.3/libio/streambuf.h:37: parse error before `}' I find this line is 35 extern "C" { 36 #include <libio.h> 37 } how can I fix this error? thanks！

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