March 2013 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Re: programme header
by ishare March 19, 2013

March 19, 2013

On Mon, Mar 18, 2013 at 03:02:02PM -0700, Ian Lance Taylor wrote: > On Sun, Mar 17, 2013 at 1:54 AM, ishare <june.tune.sea(a)gmail.com> wrote: > > > > > > when product a .so liberary , if there is not a programme header in the linker script file, > > will the linker automaticlly generate a deault one for use ? > > Yes. > > > If I write the programme header manully , need I write it before writing section command ? > > No. I am linking my kernel by a link script. its contens is as below: ********************************************************************* VSYSCALL_BASE = 0xffffe000; SECTIONS { . = VSYSCALL_BASE + SIZEOF_HEADERS; .hash : { *(.hash) } :text .dynsym : { *(.dynsym) } .dynstr : { *(.dynstr) } .gnu.version : { *(.gnu.version) } .gnu.version_d : { *(.gnu.version_d) } .gnu.version_r : { *(.gnu.version_r) } /* This linker script is used both with -r and with -shared. For the layouts to match, we need to skip more than enough space for the dynamic symbol table et al. If this amount is insufficient, ld -shared will barf. Just increase it here. */ . = VSYSCALL_BASE + 0x400; .text : { *(.text) } :text =0x90909090 .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr .eh_frame : { KEEP (*(.eh_frame)) } :text .dynamic : { *(.dynamic) } :text :dynamic .useless : { *(.got.plt) *(.got) *(.data .data.* .gnu.linkonce.d.*) *(.dynbss) *(.bss .bss.* .gnu.linkonce.b.*) } :text } PHDRS { text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */ dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */ } ******************************************************************************* I think it will work ,but ld report that "No enough room for programme header",what is the reason? what should I do ? thanks! > Ian

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signals handling: kill() successful, but nothing delivered
by michi1＠michaelblizek.twilightparadox.com March 18, 2013

March 18, 2013

Hi! I am trying to test for signal handling race conditions (specifically, I suspect the kernel side of connect() does interesting things if the server response arrives while the program executes a signal handler) and want to flood a program with lots of signals. So I have run this: --- #!/bin/bash while [ 1 -eq 1 ]; do killall -s SIGURG wget 2> /dev/null done --- ...and then then executed: strace wget -O - "http://kernel.org" ... connect(3, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("198.145.20.140")}, 16) = ? ERESTARTSYS (To be restarted) --- SIGURG (Urgent I/O condition) @ 0 (0) --- connect(3, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("198.145.20.140")}, 16) = ? ERESTARTSYS (To be restarted) --- SIGURG (Urgent I/O condition) @ 0 (0) --- connect(3, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("198.145.20.140")}, 16) = 0 ... It shows that signals arrive, but no interesting behaviour yet. I suspect this is because the rate signals are sent is too low. So I come up with this: --- #include <sys/types.h> #include <signal.h> #include <stdio.h> int main(int argc, char **argv) { int pid; int rc = 0; if (argc < 2) return 1; pid = atoi(argv[1]); if (pid <= 1 || pid >= 65536) return 1; printf("kill %d %d\n", pid, SIGURG); while (kill(pid, SIGURG) == 0) { printf("signal sent\n"); /* probably slow, remove later */ } perror("killloop end"); return 0; } --- #!/bin/bash while [ 1 -eq 1 ]; do ./a.out `ps a|grep wget|grep -v grep|sed "s/^[^0-9]*$[0-9]*$.*$/\1/"` done --- The output looks like this: kill 15574 23 signal sent signal sent signal sent ... signal sent signal sent signal sent killloop end: No such process However, no signal arrives. But if I change SIGURG to SIGTERM, they arrive! Why does SIGURG arrive when sent with "killall -s SIGURG wget", but not when sent with my test prog? -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com

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creat all the dentry objects in memory when mount a fs?‏
by RS March 18, 2013

March 18, 2013

when a new unlike-Unix filesystem mounted on my Linux system , will it creat all the dentry objects in the meory , or will it creat only needed, and is the same to inode objects ? So , if all the dentry objects created , I think it must consume a large memory.

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FW: No Subject
by Anders Lind March 18, 2013

March 18, 2013

http://www.rugbyleaguesamoa.com/uktzprd/ale.ppgt 3/18/2013 12:39:33 PM = Anders Lind =

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Re: Re: for interested folks, i'll announce new kernel tutorials via twitter
by Alexandre Borges March 18, 2013

March 18, 2013

Mrs, Good morning. Yes, I agree with Rohan.In my opinion, if someone has any problem in receiving your message, I strong suggest that he/she delete it. Simple like that. I´m interested in your e-mails and tutorials and you shouldn´t stop sending them because everewhere there are strange people who see problems where there isn´t one. Have a nice day. Alexandre Borges (br.linkedin.com/in/aleborges) On Seg 18/03/13 03:01 , rakesh Bhaskar everfriendlyrakesh(a)gmail.com sent: i agree sending on this list is a better option with some tag. so that organizing it would be much easier. Thanks On Mon, Mar 18, 2013 at 10:58 AM, Rohan Puri wrote: On Sun, Mar 17, 2013 at 7:07 PM, Robert P. J. Day wrote: as i don't want to seem like i'm spamming this list with notes about new, posted kernel tutorials, people who want to stay on top of these are welcome to follow me on twitter at @rpjday. everything written and posted will be freely available (creative commons license), and even after it's incorporated into future training courses, even those courses will be released under the CC so you'll never lose access to any of it. so feel free to play along. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca [1] Twitter: http://twitter.com/rpjday [2] LinkedIn: http://ca.linkedin.com/in/rpjday [3] ======================================================================== _______________________________________________ Kernelnewbies mailing list Kernelnewbies(a)kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies [4] Hi Robert, Its fine with me also, by sending it on this list, I think lots of people would be benefited. - Rohan _______________________________________________ Kernelnewbies mailing list Kernelnewbies(a)kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies [5] -- G B Rakesh

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A question on the vale of memory water marks
by larmbr zhan March 18, 2013

March 18, 2013

Hi, all. In "mm/page_alloc.c: __setup_per_zone_wmarks(void)" Look this: --- snip --- zone->watermark[WMARK_LOW] = min_wmark_pages(zone) + (tmp >> 2); zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1); --- snip --- after min_wmark_pages(zone)(that is watermark[WMARK_MIN]) is calculated, the watermark[WMARK_HIGH] and watermark[WMARK_LOW] are based on it. And FYI, for non-highmem zones, watermark[WMARK_MIN] is exactly tmp. That said, watermark[WMARK_HIGH] = 1.5 times watermark[WMARK_MIN] watermark[WMARK_LOW] = 1.25 times watermark[WMARK_MIN] So we came to that question, are the relation among them are just established by usage or just by empirical formula? -- Regards, Zhan Jianyu

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hpet misc device usage
by Kevin Wilson March 18, 2013

March 18, 2013

Hi, Does anybody knows about a user space utility or tool which uses the hpet misc device (/dev/hpet)? http://lxr.free-electrons.com/source/drivers/char/hpet.c rgs, Kevin

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Invitation to connect on LinkedIn
by Ashish Anand via LinkedIn March 17, 2013

March 17, 2013

LinkedIn ------------ Ashish Anand requested to add you as a connection on LinkedIn: ------------------------------------------ Deepak, I'd like to add you to my professional network on LinkedIn. - Ashish Accept invitation from Ashish Anand http://www.linkedin.com/e/8z2206-hee2gyab-6f/L90NvsYL3GREvJdnM0f-HnfkWNbSD_… View profile of Ashish Anand http://www.linkedin.com/e/8z2206-hee2gyab-6f/rso/165943060/0fsy/name/494894… ------------------------------------------ You are receiving Invitation emails. This email was intended for Deepak Shah. Learn why this is included: http://www.linkedin.com/e/8z2206-hee2gyab-6f/plh/http%3A%2F%2Fhelp%2Elinked… (c) 2012, LinkedIn Corporation. 2029 Stierlin Ct, Mountain View, CA 94043, USA.

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kmem_cache_init
by ishare March 17, 2013

March 17, 2013

the function kmem_cache_init() is allocating which area for whom to use ? what is the difference comparing with vfs_caches_init() ? thanks!

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now in progress -- tutorial on udev
by Robert P. J. Day March 16, 2013

March 16, 2013

a bit premature but the simple "USB devices" page i started earlier was to allow me to set the stage for a tutorial on udev i've wanted to write for a while. it's *barely* started, but it's here: http://www.crashcourse.ca/wiki/index.php/Udev and will use as the basis for a hands-on example the aforementioned USB-serial cable, since that seemed like the simplest device i could expect others could lay hands on if they wanted to follow along and actually watch udev processing in real time. much more to come on the udev page by end of day ... rday p.s. if others have a suggestion for a device that could be used for hands-on udev that's cheap, easy to find and doesn't overwhelm the beginner with udev processing, i'm open to suggestions. again, all this will eventually end up in one of my courses, no idea where yet. -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================

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