August 2002 - Darwin-kernel

Re: lseek in a KEXT
by Justin C. Walker 07 Aug '02

07 Aug '02

On Wednesday, August 7, 2002, at 10:02 AM, David Blanton wrote: if lseek is libc and not available why is the symbol for lseek in the kext symbol file? I dunno. Do you call 'lseek()' in your extension? Is the symbol defined or undefined? I have no idea how you got the kext symbol file, or how you built the extension, so it's pretty difficult to answer your question. You can, of course, execute 'ld' with a reference to your extension and libc, and get something which may appear to be successfully linked. The result will blow up in your face, once you light the fuse, of course. Regards, Justin -- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | Men are from Earth. | Women are from Earth. | Deal with it. *--------------------------------------*-------------------------------* _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

Re: lseek in a KEXT
by David Blanton 07 Aug '02

07 Aug '02

if lseek is libc and not available why is the symbol for lseek in the kext symbol file? On Wednesday, August 7, 2002, at 10:19 AM, Justin C. Walker wrote: On Wednesday, August 7, 2002, at 09:05 AM, David Blanton wrote: I want to use lseek from my KEXT. The function definition is not in unistd.h as the man page indicates ... ergo compile error. But, inspection of the KEXT symbol file shows lseek. So, can someone tell me how to use lseek from my KEXT? Can't be done. lseek is a libc function, and libc is generally not available in kernel extensions. If you have file operations to do, use a user-mode application, where libc is available. Regards, Justin -- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | Men are from Earth. | Women are from Earth. | Deal with it. *--------------------------------------*-------------------------------* _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored. David Blanton Elisar Software Corporation Albuquerque _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

Re: lseek in a KEXT
by Justin C. Walker 07 Aug '02

07 Aug '02

On Wednesday, August 7, 2002, at 09:05 AM, David Blanton wrote: I want to use lseek from my KEXT. The function definition is not in unistd.h as the man page indicates ... ergo compile error. But, inspection of the KEXT symbol file shows lseek. So, can someone tell me how to use lseek from my KEXT? Can't be done. lseek is a libc function, and libc is generally not available in kernel extensions. If you have file operations to do, use a user-mode application, where libc is available. Regards, Justin -- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | Men are from Earth. | Women are from Earth. | Deal with it. *--------------------------------------*-------------------------------* _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

lseek in a KEXT
by David Blanton 07 Aug '02

07 Aug '02

I want to use lseek from my KEXT. The function definition is not in unistd.h as the man page indicates ... ergo compile error. But, inspection of the KEXT symbol file shows lseek. So, can someone tell me how to use lseek from my KEXT? David Blanton Elisar Software Corporation Albuquerque _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

Re: How to develope a video driver?
by David A. Gatwood 06 Aug '02

06 Aug '02

On Mon, 5 Aug 2002, Alberto wrote: > I have an old video card with TV/in and I would like to know if is possible > to develop an OS X driver to use it? Assuming that it works in a machine that Mac OS X supports, do you have at least one of the following: 1. A Linux, *BSD, or other driver source for it, 2. Documentation on the chipset used, or 3. A computer running another OS with working drivers, a bus analyzer, and a lot of free time? If so, then yes. If not, you should probably try to contact the manufacturer and try to obtain one of these things. As always, the question of which one to obtain is a matter of personal preference. ;-) If memory serves, there are examples of video drivers for a handful of non-accelerated video devices in the Darwin repository that should be useful as a starting point. Later, David --------------------------------------------------------------------- David A. Gatwood dgatwood(a)gatwood.net Developer Docs Writer dgatwood(a)apple.com Apple Computer dgatwood(a)mklinux.org Check out my weekly web comic: http://www.techmagazine.org _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

How to develope a video driver?
by Alberto 06 Aug '02

06 Aug '02

People, I have an old video card with TV/in and I would like to know if is possible to develop an OS X driver to use it? Regards, Alberto V. M. _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

Re: Mac OS X - VM Working Set
by Jim Magee 05 Aug '02

05 Aug '02

On Saturday, July 27, 2002, at 05:43 PM, luisella wrote: Hello, I'm studying Darwin kernel and I found some information about working set on Mach Virtual Memory. "The first time that an application is launched in a given user context, the initial working set required to start the application is captured and stored in a file..... /var/vm/app_profile". Why I didn't find this file into my iMac with OS X 10.1.5? In Mac OS X 10.1.x (Darwin 5), the VM system would dynamically track working sets of running applications and use that for page replacement/fetch purposes. But the cache of early working set info across launches is new to Mac OS X 10.2 (Darwin 6). --Jim _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

Locking up in waitevent
by Chris Leishman 05 Aug '02

05 Aug '02

Hi all, I was playing around with the event queue calls (on MacOSX 10.1.5) and have found a strange blocking issue with the waitevent syscall. The second argument to waitevent is a struct timeval, specifying a timeout for the polling action. The syscall is meant to return when an event is ready or the time expires. In some situation(s) waitevent appears to ignore the timeout and block indefinitely. This cannot be reproduced exactly, but can be reproduced by continuously calling waitevent with a timeout of 0 (which should cause it to return immediately if no events are available) - until it locks. This takes a very short amount of time (average of about 30000 calls). Example code is below, and should be run as follows: ./a.out 2> out When the output file stops growing, waitevent has locked (gdb has be used to confirm this). I would like to investigate this further, by debugging the kernel code for the syscall. Does anyone have a link or information regarding compiling the darwin kernel for MacOSX ? I don't have access to a second machine to run darwin exclusively - so this is my only option. Regards, Chris Leishman eventtest.c ----------------------------- #include <sys/ev.h> #include <sys/time.h> #include <sys/syscall.h> #include <unistd.h> #include <stdio.h> // These aren't defined in the system headers (on MacOSX 10.1.5) #define watchevent(a,b) syscall(231,(a),(b)) #define waitevent(a,b) syscall(232,(a),(b)) #define modwatch(a,b) syscall(233,(a),(b)) int main(void) { struct eventreq theCurrentEvent; struct timeval tv; int i = 0; int result; tv.tv_sec = 0; tv.tv_usec = 0; for (;;) { fprintf(stderr, "Calling waitevent: %d\n", i++); result = waitevent(&theCurrentEvent, &tv); fprintf(stderr, " result: %d\n", result); } return 0; } _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

Re: ps v. top
by Justin C. Walker 01 Aug '02

01 Aug '02

On Wednesday, July 31, 2002, at 01:27 PM, David Blanton wrote: When a CFM app is launched the path name passed to execve is ../LaunchCFMApp. Yes, ps -auww shows the CFM name. If TOP is running when a CFM app is launched it immediately shows the CFM app name in the 'Command' column. So the question is ... at execve time with a CFM app where is the CFM app name available? I believe that most of the actual exec/launch magic is done by dyld. Check the 'top' subproject of system_cmds. The command looks for LaunchCFM and then goes off to figure out what the real command/app is. Regards, Justin -- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | When LuteFisk is outlawed | Only outlaws will have | LuteFisk *--------------------------------------*-------------------------------* _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0

Re: How do disk writes work these days?
by Paul Ripke 01 Aug '02

01 Aug '02

On Wednesday, July 31, 2002, at 08:16 , Justin C. Walker wrote: On Tuesday, July 30, 2002, at 02:51 PM, Pelle Johansson wrote: torsdagen den 25 juli 2002 kl 03.15 skrev Wade Tregaskis: Is this still an efficient way of operating, in an increasingly linear [e. g. single-user] OS? I'm just thinking, if you could return from writes faster, the calling process can keep doing other things. My thought is that you could do this without breaking existing apps by performing any error checking [i.e. quickly verifying there is free space, among other things] immediately, returning fail if appropriate, or otherwise returning no error. You could then worry about physically getting the data to disk, seeing as this is the most time intensive part... Side note: I was taught that if you know how large a file you want to write you should use ftruncate() to set the file size before writing. That way the OS can optimize the location of the file on the hard drive. I've noticed Unix application are quite bad at doing this, so perhaps it doesn't apply in some OSes. Most Unices won't take advantage of this 'optimization', because the typical Unix file system allows 'holes' in the allocation. Thus, if you create an empty file, and truncate (or seek to a far corner of the universe), and write a byte, the intervening space will *not* be allocated. This is dependent on the type of file system, of course. The HFS+ file system does not support 'holes'. A.K.A. sparse files, and depending on the backup tool used, can make life with Oracle databases interesting (think a tool which "makes" holes when restoring zeroed blocks, and the filesystem fills up six months later for no apparent reason...) Always cute to see in the flesh - this is on a NetBSD box: bash$ df -k . Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/wd1a 3942626 1791392 1954102 47% /export/home bash$ touch sparse bash$ dd if=/dev/zero of=sparse bs=4k count=1 seek=4m 1+0 records in 1+0 records out 4096 bytes transferred in 0.001 secs (4096000 bytes/sec) bash$ ls -l sparse -rw-r--r-- 1 stix users 17179873280 Aug 1 23:47 sparse bash$ du -sk sparse 24 sparse bash$ Cheers, -- Paul Ripke Unix/OpenVMS/DBA 101 reasons why you can't find your Sysadmin: 68: It's 9AM and they're not working that late. _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

1 0