January 2003 - Darwin-kernel

Re: Building the kernel 6.0.2
by Quinn 21 Jan '03

21 Jan '03

At 16:48 -0600 20/1/03, Brian_Tabone wrote: This may have been asked before on this list, I apologize if this is a repeat. What is Apple's official policy in regards to synchronizing the public darwin CVS repository with its internal CVS repository. I don't think Apple has a publicly-stated official policy on this. I know it's something that we've wrestled with internally a lot, but I don't think it has ever resolved well enough to issue an official policy. Sorry. S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Technical Support * Networking, Communications, Hardware _______________________________________________ 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.

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kreate kmod kall-in kpi?
by David Krauss 21 Jan '03

21 Jan '03

In mach/host_priv.h, there's a really neat-looking function: kern_return_t kmod_control ( host_priv_t host_priv, kmod_t module, kmod_control_flavor_t flavor, kmod_args_t *data, mach_msg_type_number_t *dataCnt ); It looks like it'll call a function "flavor" in a kmod "module" with parameters "data"/"dataCnt". I don't see where info gets returned (mebbe ptr/data passed back is changed?), but I don't need anything more than a return_t anwyay. Does this do what it looks like? Is it the best way of executing some arbitrary code in the kernel? So, how do I associate a function in my kmod wth a control_flavor? Also, what's the preferred method of loading a kmod from application code? Should I read it into the app's address space & call kmod_create() or run kmodload? Or mebbe elsehow? Is there documentation to the kmod interface? Was it interited from somewhere in particular or is it new in Darwin? - TIA, David "Potatoswatter" Krauss Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com _______________________________________________ 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.

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Re: Building the kernel 6.0.2
by Brian_Tabone 20 Jan '03

20 Jan '03

Quinn, This may have been asked before on this list, I apologize if this is a repeat. What is Apple's official policy in regards to synchronizing the public darwin CVS repository with its internal CVS repository. Basically, how long does apple target between releasing an OS update and releasing that full APSL source to the public CVS repository. -Sincerely, Brian Tabone On Monday, January 20, 2003, at 10:30 AM, Quinn wrote: At 20:42 -0800 16/1/03, Jeff Jenkins wrote: BTW, are the sources found in xnu the same as those provided in a Mac OS X install? No. I mean, if I build mach_kernel will it work if I replace the mach_kernel that is provided as part of Mac OS X? Yes. There are very minor differences between the sources that Apple uses to build production Mac OS X kernels and the Darwin sources. The differences are sufficiently minor that X boots just fine using a Darwin-built kernel. In fact, I do this regularly when debugging (while I have access to Apple's sources, it's better if I can get away with using only public resources when helping third party developers). S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Technical Support * Networking, Communications, Hardware _______________________________________________ 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. _______________________________________________ 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.

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re: Building the kernel 6.0.2
by Quinn 20 Jan '03

20 Jan '03

At 20:42 -0800 16/1/03, Jeff Jenkins wrote: BTW, are the sources found in xnu the same as those provided in a Mac OS X install? No. I mean, if I build mach_kernel will it work if I replace the mach_kernel that is provided as part of Mac OS X? Yes. There are very minor differences between the sources that Apple uses to build production Mac OS X kernels and the Darwin sources. The differences are sufficiently minor that X boots just fine using a Darwin-built kernel. In fact, I do this regularly when debugging (while I have access to Apple's sources, it's better if I can get away with using only public resources when helping third party developers). S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Technical Support * Networking, Communications, Hardware _______________________________________________ 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.

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Re: cvs access from eclipse
by Richard Morgan 20 Jan '03

20 Jan '03

Never mind, it started working today. Guess there's a little lag time between http access and pserver access. Rick _______________________________________________ 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.

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Re: darwin-kernel digest, Vol 2 #203 - 4 msgs
by Shawn Erickson 19 Jan '03

19 Jan '03

John, Hard to answer your question without knowing a little more information about the state of your system when you are seeing what you are reporting. Also it can vary depending on system hardware and its configuration. Obviously if swapping is needed in order to support some operation you are trying to do and that swap IO is competing with other IO to the same disk resource then you could see delays. I am not sure of RAM utilization on your system when you are seeing what you report to know if this is a candidate. Activating the window may also incur some IO if the application is something like the Finder. So be aware of that as well. It sounds like a resource issue it just very hard to tell what resource: PCI bus, CPU, system RAM, Disk, etc. Anyway, if you can give additional information I could speculate what may be the cause. --- Matthias/John, Regarding what is in Darwin (and Mac OS X)... The Darwin kernel has a unified buffer that both the VM system and file cache utilize. Basically nearly all of system RAM can be used to store file data by the file cache but this data is dropped if the RAM is needed in order to service application RAM needs (any process). If you watch a system in top you can see the number of free pages go down and the number of inactive go up as you pull file data through the system. This is the file cache going to work. I do not believe that any write cashing is done at this point in time. Not because it isn't possible but because the hardware that most run Mac OS X on is not well setup for lazy writing. What if the power goes out, cosmic rays hit your ram, etc. In UPSed environments I could see doing write caching. I do believe that some amount of lazy writing of the file system structures is currently done but not for file system data. Inactive pages can also hold pages related to application executables, libraries and such. Nothing is really dumped out of RAM unless the RAM is needed for something else. This way disk IO can be avoided. Most likely more intelligent reuse algorithms could be added but... In more recent kernels, actually I think the functionality is outside of the kernel, application working set is tracked, analyzed, and recorded. Basically the OS is trying to learn and remember the most likely working sets of applications (which can vary depending on how users work in them) so that the next time the application is launched the most likely pages can be preloaded before a fault is hit. -Shawn On Sunday, January 19, 2003, at 07:40 AM, John Hunter wrote: Hi, I'm sure there are lots of ways to optimise caching, but my question is: why does one process causing a lot of disk access slows down a whole lot other processes which you would think don't require so much disk access (like the Window Manager when you drag a window...). I haven't seen this kind of behaviour with other UNIX systems. John Hello! First of all, I don't know what is implemented in the darwin kernel at all, but here are some of my thoughts about this topic: Preventing disk access for starting applications if nearly impossible, because the data has to be read out for it. It can only be improved by caching all data that was read or reading out sequentially (if possible) data, that will be used. In an offline-situation it is possible to calculate what is the best way to read and cache disk-data, but in the online-situation it is somehow hard to tell which data could be read next. It is easy to guess if someone opens a file, that and begins to read it sequentially, that he could read the whole file, so the system could begin to cache it, if memory is available and no other disk-access is forced. This all shouldn't be a problem which is new to the world, so one should find some online-algorithms with a good competivness in the appropriate text-books. One question would be, how swapping is implemented. There has to be some way of telling the system, that the swap files don't have to be cached. Caching of swap-space is somehow stupid :) By using caches, one could also cache disk-write-access, trying to reduce disk-access at all, enhancing spin-down-times and for mobile users this should reduce battery usage. I was thinking of it some while ago, but hadn't had the time to look at the different parts of darwin related to disk-access. _______________________________________________ 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. _______________________________________________ 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.

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Re: darwin-kernel digest, Vol 2 #203 - 4 msgs
by John Hunter 19 Jan '03

19 Jan '03

Hi, I'm sure there are lots of ways to optimise caching, but my question is: why does one process causing a lot of disk access slows down a whole lot other processes which you would think don't require so much disk access (like the Window Manager when you drag a window...). I haven't seen this kind of behaviour with other UNIX systems. John Hello! First of all, I don't know what is implemented in the darwin kernel at all, but here are some of my thoughts about this topic: Preventing disk access for starting applications if nearly impossible, because the data has to be read out for it. It can only be improved by caching all data that was read or reading out sequentially (if possible) data, that will be used. In an offline-situation it is possible to calculate what is the best way to read and cache disk-data, but in the online-situation it is somehow hard to tell which data could be read next. It is easy to guess if someone opens a file, that and begins to read it sequentially, that he could read the whole file, so the system could begin to cache it, if memory is available and no other disk-access is forced. This all shouldn't be a problem which is new to the world, so one should find some online-algorithms with a good competivness in the appropriate text-books. One question would be, how swapping is implemented. There has to be some way of telling the system, that the swap files don't have to be cached. Caching of swap-space is somehow stupid :) By using caches, one could also cache disk-write-access, trying to reduce disk-access at all, enhancing spin-down-times and for mobile users this should reduce battery usage. I was thinking of it some while ago, but hadn't had the time to look at the different parts of darwin related to disk-access. _______________________________________________ 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.

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Apple's policy on updating CVS
by Jeff Jenkins 19 Jan '03

19 Jan '03

As a newbie to Darwin, please excuse my ignorance. What is Apple's policy for updating the CVS repository with sources once a commercial release has been done? Since Mac OS X 10.2.3 is out, when will the sources for the xnu kernel be available? Also, how does one map the label/tag given to a production release to what's in CVS? For example, if I % hostname, I see xnu has a lable of xnu-344.23. When will this hit CVS? BTW, the APPLE-344-12-2 label is missing vfs_journal.h/c files...?? Thanks for the patience with these bone-headed questions! : ) -- jrj _______________________________________________ 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.

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Re: Booting alternative kernels from primary disk?
by Jean-Pierre Mouilleseaux 18 Jan '03

18 Jan '03

"Before you install the new kernel, make a copy of your original kernel. When things fail you can always copy the original kernel back by booting from a different disk or partition. Either X or 9 will work." (from xnu building for mortals - circa 10.1.1) I am rather speechless. This seems like a rather obsolete suggestion for machines that ship with solely OSX now. Is there no such way to boot from the backup kernel you made from the primary disk?. I only have X, I don't have 9. I also only have one Mac. Do I need to keep the original install cd's on hand whenever I am in the mood to dabble? i wrote a simple script to safely swap out kernel builds that might be mildly helpful. to the best of my knowledge, the script only works on ppc machines -- i am unsure how darwin x86 handles its nvram variables (or more specifically boot-device). if madness ensues and the machine fails to boot, you can zap the pram (command-option-p-r) to restore the default boot-device settings. while i have not managed to mess up my boot driver, do keep in mind what josh said about booting off another partition or cd to restore the driver. kswap: <http://opendarwin.org/~jpm/naughty/darwin/kswap.sh> hope this helps. cheers, jean-pierre _______________________________________________ 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.

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cvs access from eclipse
by Richard Morgan 18 Jan '03

18 Jan '03

I set up my Eclipse cvs configuration to access the Darwin source code, and upon completion it creates a connection string like the one posted by Michael Kress previously: :pserver:rkmorgan@anoncvs.opensource.apple.com:/cvs/Darwin However, it won't connect, I get an "I/O has been interrupted" message. I have the timeout set to 40 seconds, so thats not the problem (right?) and I have no trouble downloading code using the web browser interface, so I know the username password is correct. Are there any issues with Eclipse downloading code or something special I have to do? I'm using the M4 Eclipse build which I believe is the latest. thanks, Rick _______________________________________________ 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.

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