July 2003 - Darwin-kernel - lists.apple.com

Re: Current Directory of a Process
by Quinn 10 Jul '03

10 Jul '03

At 9:58 -0400 10/7/03, Robert Sandilands wrote: I have seen that basically all file access does provide the full path except the Terminal. I guess it depends on whether you want a 100% solution, or just a statistically significant one. To keep track of the current directory you just have to keep track of all SYS_chdir calls... But it is really ugly, but not as ugly as the solutions you mention. Indeed. If I could add a feature request wish for a future version of the kernel, I would like to see a variable somewhere that stores the current working directory on a per process basis. The best place to put such feature requests is into our bug tracking database. Please include a high-level description of what you're trying to do and how the feature would facilitate your product. <http://developer.apple.com/bugreporter/> These go directly to the engineers responsible. I get the impression that your design is predicated on patching the system call table? If so, I feel compelled to warn you that this is unlikely to be binary compatible with future releases of Mac OS X. If you base a product on this technology and ship that product to end users, you must be prepared to release updates as we update Mac OS X. 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: Current Directory of a Process
by Robert Sandilands 10 Jul '03

10 Jul '03

I have seen that basically all file access does provide the full path except the Terminal. To keep track of the current directory you just have to keep track of all SYS_chdir calls... But it is really ugly, but not as ugly as the solutions you mention. If I could add a feature request wish for a future version of the kernel, I would like to see a variable somewhere that stores the current working directory on a per process basis. If you think about it, 1024 bytes extra per process is not that much of a performance penalty in a modern world? On my machine as it is running now, with about 10 applications open, it means 68kB more memory used by the kernel. I know I am simplifying it quite a bit. The path does not have to be unique or even correct, it just needs to be one path that does work. I think there are a significant number of applications that will suffer performance penalties because it is so slow/difficult to get to the current working directory. I have seen at least one complaint of the slow performance of darwin because of this. Look at an email "Performance of realpath" on the darwin-development mailing list about slow performance of PHP. Thank you Robert Sandilands On Thursday, July 10, 2003, at 05:03 AM, Quinn wrote: At 12:17 -0400 11/6/03, Robert Sandilands wrote: I am open to any suggestions. Lots of folks ask for this (vnode to path), but it's just not possible in the general case within the current architecture. As Jim said, there may not be a path, or there may be more than one. There are two really ugly options. 1. If the vnode is a directory, you can follow up the .. chain until you hit the root, at each stage iterating through the directory looking for your vnode. This is exactly the algorithm used by getcwd_physical in Libc. 2. If the vnode is a file, there's no general solution. The only feasible approach that I've seen is to get the CNID for the file and its parent, and then use volfs to look up the file and find its parent. This approach will only work on file systems that support volfs (HFS [Plus], AppleShare). You really have to stand back and look at the overall problem. How are you tapping into the kernel to generate your log points? Can you use that same mechanism to keep track of this information on a pre-process basis? Regardless, it's very likely that any approach you take will result in *serious* binary compatibility problems as we evolve the Mac OS X kernel. The kernel architecture just isn't set up to do this. --------------------------------------------------------------------- #include http://robert.rsa3.com/disclaimer.html _______________________________________________ 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: bdevsw_add() is broken
by Quinn 10 Jul '03

10 Jul '03

At 11:24 +0200 10/7/03, Markus Hitter wrote: Thanks for the link, Quinn. It's even clickable in Mail.app. It doesn't work, however. Could you please add a Radar about non-working rdar: links ? ;-) It works with the internal Radar client that I have here. I realise that it's not helpful for external developers, but then again, neither is "Radar ID 3019079", which is how I used to quote Radar numbers. At least in the new format it's helpful for me (-: and other Apple folk. 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: bdevsw_add() is broken
by Markus Hitter 10 Jul '03

10 Jul '03

Am Donnerstag, 10.07.03 um 10:59 Uhr schrieb Quinn: I believe that this is a known bug <rdar://problem/3019079> which should be fixed in Panther. Thanks for the link, Quinn. It's even clickable in Mail.app. It doesn't work, however. Could you please add a Radar about non-working rdar: links ? ;-) Have fun, Markus - - - - - - - - - - - - - - - - - - - Dipl. Ing. Markus Hitter http://www.jump-ing.de/ _______________________________________________ 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: Current Directory of a Process
by Quinn 10 Jul '03

10 Jul '03

At 12:17 -0400 11/6/03, Robert Sandilands wrote: I am open to any suggestions. Lots of folks ask for this (vnode to path), but it's just not possible in the general case within the current architecture. As Jim said, there may not be a path, or there may be more than one. There are two really ugly options. 1. If the vnode is a directory, you can follow up the .. chain until you hit the root, at each stage iterating through the directory looking for your vnode. This is exactly the algorithm used by getcwd_physical in Libc. 2. If the vnode is a file, there's no general solution. The only feasible approach that I've seen is to get the CNID for the file and its parent, and then use volfs to look up the file and find its parent. This approach will only work on file systems that support volfs (HFS [Plus], AppleShare). You really have to stand back and look at the overall problem. How are you tapping into the kernel to generate your log points? Can you use that same mechanism to keep track of this information on a pre-process basis? Regardless, it's very likely that any approach you take will result in *serious* binary compatibility problems as we evolve the Mac OS X kernel. The kernel architecture just isn't set up to do this. 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: getting process info for a kext
by Quinn 10 Jul '03

10 Jul '03

At 13:33 -0700 10/6/03, Chris Silverberg wrote: I have an existing kext that needs to be modified slightly to look at process information. The most supportable answer to this is to move the code that needs to do the sysctl into user space. Might it be possible to do that part of the work in user space? Failing that, my next question is, what context is your KEXT running in? Doing any sysctl work will require you to acquire the BSD system funnel. If you're running in the context of an I/O Kit driver, you're probably not holding any funnels. If you're running in an NKE, you're probably holding the wrong (network) funnel. Even if you're holding the right funnel, I don't think this is going to work. sysctl expects to copy its data in to and out of the user memory space of the current thread. Take a look at sysctl_int in "xnu/bsd/kern/kern_sysctl.c"; see how it blindly calls copyin/copyout. I believe that the traditional approach for accessing sysctl-like things in the kernel is to just access the variables directly. sysctl is specifically designed to allow user space code access to these variables. It doesn't make a lot of sense to call it from kernel code in the traditional UNIX model. OTOH, now that we're concerned about binary compatibility for kernel extensions it might make sense to support sysctl from kernel code. Something to think about when we publish the Kernel Programming Interfaces (KPI) specification for developer comment. 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: DSI wrapper & AFP - tickles
by Quinn 10 Jul '03

10 Jul '03

At 12:02 -0700 12/6/03, andre(a)hugesystems.com wrote: I was just curious if there was open source available for the DSI (data stream interface ?) wrapper around AFP. No. There have been some efforts internally to open source the AFP client, but it hasn't happened yet. 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: Duplicate entries in a file system...
by Quinn 10 Jul '03

10 Jul '03

At 13:33 -0400 9/7/03, Marek Kozubal wrote: I am writing a file system that is designed to look like HFS+ to Mac OS X. Does your file system support volfs? 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: bdevsw_add() is broken
by Quinn 10 Jul '03

10 Jul '03

At 16:05 +1000 3/7/03, Sam Vaughan wrote: According to a comment in bdevsw_add() in xnu/bsd/kern/bsd_stubs.c, a fix was applied to address Radar bug 2842228. I don't know the history behind the fix, but it seems to have completely broken the function. I believe that this is a known bug <rdar://problem/3019079> which should be fixed in Panther. 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: IORegistryEntrySetCFProperty in AudioDriverPlugInStreamSetProperty
by Quinn 10 Jul '03

10 Jul '03

At 17:00 +0200 2/7/03, Alain Critet wrote: I have write an audio driver plugin that work correctly with Mac OS X 10.2.3, but with 10.2.6 I have the following problem. You might retry your question on of the following lists. <http://lists.apple.com/coreaudio-api> <http://lists.apple.com/darwin-drivers> AFAIK this list has no audio driver experts on it. 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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