November 2001 - Darwin-kernel

Re: Limitations Within a Driver
by justin＠mac.com 26 Nov '01

26 Nov '01

You can probably get this to work, but I think, in general, it's A Bad Idea. What, exactly, are you trying to achieve? Regards, Justin On Sunday, November 25, 2001, at 10:22 , Sean Morrell wrote: Can named pipes, sockets and signals be used from within a driver, specifically an I/O Kit kernel audio driver? I have been told that disk I/O cannot be performed from within a driver? Is this true? If so, does this exclude the use of a disk based IPC such as a named pipe? Thanks, Sean _______________________________________________ darwin-kernel mailing list darwin-kernel(a)lists.apple.com http://www.lists.apple.com/mailman/listinfo/darwin-kernel --- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | Men are from Earth. | Women are from Earth. | Deal with it. *--------------------------------------*-------------------------------*

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IPC Questions
by Sean Morrell 26 Nov '01

26 Nov '01

I need two processes communicating with an IPC. These processes are not in a parent/child relationship and will startup and shutdown independently. So both processes will need to rendezvous by using the same IPC key when creating or opening an IPC object such as a message queue or shared memory. How do I ensure the IPC key is unique and will not conflict with an existing or future application? Also, in creating a named pipe I need a pathname of the FIFO file to create. I have been told that modifying a driver bundle is not possible, so I guess the pipe cannot reside in the driver's kext. Is there a standard location in the directory tree where FIFOs should reside? Or should they be placed in the same path as the application? Note I believe the path will need to be hardcoded in the driver kext at build time, since I don't think it can be modified to reflect the installation path of the software at install time. Thanks, Sean

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Limitations Within a Driver
by Sean Morrell 26 Nov '01

26 Nov '01

Can named pipes, sockets and signals be used from within a driver, specifically an I/O Kit kernel audio driver? I have been told that disk I/O cannot be performed from within a driver? Is this true? If so, does this exclude the use of a disk based IPC such as a named pipe? Thanks, Sean

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xemacs kernel panics
by Ron Cohen 22 Nov '01

22 Nov '01

The reports of kernel panics with xemacs keep rolling in; in addition to the threads in http://lists.apple.com/mhonarc/darwin-development/msg10480.html there was another report posted in http://lists.apple.com/mhonarc/darwin-development/msg10498.html And to add my two cents worth, here are MY kernel panic reports from both OS 10.1 and OS 10.1.1. Note I updated my version of xemacs in between from 21.4.3 to 21.4.5, but previous experience indicated that the xemacs version didn't matter. I've also updated the version of XDarwin from 1.0a1 to 1.0a3 and then 1.0a4, and got panics with each using emacs 21.4.3. Finally: I don't think the bug is completely reproducable. With OS 10.1, I would occasionally get kernel panics on initial launch of xemacs, but more typically only after working with xemacs for several minutes. Since going to 10.1.1 I don't have as many cases to survey, since I did my best to avoid the problem once I noted it was there. In my few experiences it again took several minutes, lots of actions, before the panic occured. So I'm guessing that when the panic occurs depends on what else is going on on the machine. -Ron Cohen- p.s. for what it is worth I am running a dual processor G4/450 with 256 MB RAM. p.p.s. Avoidance strategies: (1) run xemacs in "no-window" (-nw) mode; (2) not sure about this, but it looks like xemacs run through an ssh tunnel is OK -- that is, I ssh'ed from the mac to another machine and back, and ran xemacs (in its own window) with X11 tunnelling. ------------------ Old (OS 10.1) panic(cpu 0): lockmgr: pid -2, thread 0x 180cd04, not exclusive lock holder pid -2 thread 0x 1c8e354 unlocking, exclusive count 1 Latest stack backtrace for cpu 0: Backtrace: 0x0008122c 0x000815cc 0x00027d38 0x001831b0 0x001886c8 0x00188bf8 0x00026794 0x0008ec0c 0x0008e9a0 0x0050b13e Proceeding back via exception chain: Exception state (sv=0x0c4cd000) PC=0x70001318; MSR=0x0000f030; DAR=0x01f250ce; DSIR=0x00002004; LR=0x0008449e8; R1=0xbfffe140; XCP=0x00000030 (0xC00 - System call) Kernel version: Darwin Kernel Version 1.4: Sun Sep 9 15:39:59 PDT 2001; root:xnu/xnu-201.obj~1/RELEASE_PPC Debugger(panic) Waiting for remote debugger connection ---------------------------- New (OS 10.1.1) panic(cpu 0): lockmgr: non-zero exclusive count Latest stack backtrace for cpu 0: Backtrace: 0x000819b8 0x00081d58 0x00028520 0x001840bc 0x00187d28 0x001892dc 0x00189b78 0x00026f7c 0x0008f40c 0x001920e8 0x0018a41c 0x0018a29c Proceeding back via exception chain: Exception state (sv=0x0c4cd000) PC=0x70025CAB; MSR=0x0000f030; DAR=0x01fc7aee; DSIR=0x00002004; LR=0x0078e8e4; R1=0xbfffe800; XCP=0x00000030 (0xC00 - System call) Kernel version: Darwin Kernel Version 5.1: Tue Oct 30 00:06:34 PST 2001; root:xnu/xnu-201.5.obj~1/RELEASE_PPC Debugger(panic) Waiting for remote debugger connection

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Re: Modifying Bundle's Info Property List
by Sean McBride1 22 Nov '01

22 Nov '01

Sean Morrell (smorrell(a)artlogic.com) wrote: >>We are recommending that you write a tool that you deliver a >>StartupItem that can configure your driver at start time. > >StartupItem? Can you give me a brief description? It is an application that runs at startup, BEFORE a user logs in. You could communicate with your driver from such an application. Our driver also needs to configure itself based on user settings. My plan is: 1- startup item runs at startup time 2- it forks itself. the parent quits and the child runs forever (this seems to be needed since if the parent never ends, the login window never comes up) 3- the child process watches for user logins, when this happens it uses CFPreferences to get the user prefs. The watching is done with APIs in SystemConfiguration.h 4- the child sends the info to the driver I have successfully got to step 2. But I think it will all work. You might look at: <http://www.opensource.apple.com/projects/documentation/howto/html/ SystemStarter_HOWTO.html> hth,

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Re: Modifying Bundle's Info Property List
by Sean Morrell 22 Nov '01

22 Nov '01

gvdl(a)apple.com writes: >Sean, > >I think you are trying to store persistent data in your KEXT's >Properties. I'm afraid that isn't gonna work. The main issue is >that the drive bundle itself is intended to be immutable. In fact >Apple intends to sign every bundle that is loaded into the kernel and >if you modify the bundle then your signature will fail and we will >either refuse to load you or leave it up to the user. In a DTS call, someone suggested this method of reconfiguring the driver. When is this signature created? We must (do to some device pecularities) reload the driver during this configuration change. Will this workaround the signature problem? > > >Now IOKit doesn't have a persistent data base as yet. We are >exploring a number of ideas but none of them are ready for prime time >yet. > >We are recommending that you write a tool that you deliver a >StartupItem that can configure your driver at start time. StartupItem? Can you give me a brief description? > > >See the archive on this subject as it is a hardy perennial topic on >darwin. > >Godfrey > > >>I don't know which conference these questions are best suited. Please >>tell me if this message needs to be redirected. I'm using the Core >>Foundation Bundle services to obtain the information property list for a >>driver bundle using the routine CFBundleGetInfoDictionary. However this >>routine returns an immutable reference and I need to modify this >>information property list. How can I modify the information property >list >>for the bundle? Also since the bundle is a driver and will reside in >>/System/Library/Extensions, will I have a file access issue? The >property >>list is being modified from a system preference pane in user space. How >>do I get the necessary access?

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Re: Modifying Bundle's Info Property List
by Shawn Erickson 21 Nov '01

21 Nov '01

On Wednesday, November 21, 2001, at 08:47 AM, Stiphane Sudre wrote: Also since the bundle is a driver and will reside in /System/Library/Extensions, will I have a file access issue? Wouldn't it be possible to add it to the /Library/Extensions folder instead ? (I don't know if it would work). Is /Library/Extensions a valid / expected place for third party kexts to go (it makes sense to me)? I was under the impression that only /System/Library/Extensions would work for kexts. -Shawn

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Re: User / Kernel
by Sean Morrell 21 Nov '01

21 Nov '01

gvdl(a)apple.com writes: >Is your driver an IOAudio class? Yep. > > >Godfrey > >At 19:19 -0800 01-11-20, Sean Morrell wrote: >>Actually, the driver is for an audio device. And the user space >>application is nothing more than a system preference pane, needed only to >>configure the device. The audio device has some pecularities making it >>unconfigurable using the typical CoreAudio interface. I do have the >>option of using an Audio HAL Plug-In. But I just wanted to see if >another >>IPC method might quicken the development. At this time, I simply need a >>one way notification to the driver. Eventually the driver will need to >>respond to the preference pane, returning small structures of data. In >>both cases, what IPC would you recommend?

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Re: User / Kernel
by Godfrey van der Linden 21 Nov '01

21 Nov '01

Is your driver an IOAudio class? Godfrey At 19:19 -0800 01-11-20, Sean Morrell wrote: Actually, the driver is for an audio device. And the user space application is nothing more than a system preference pane, needed only to configure the device. The audio device has some pecularities making it unconfigurable using the typical CoreAudio interface. I do have the option of using an Audio HAL Plug-In. But I just wanted to see if another IPC method might quicken the development. At this time, I simply need a one way notification to the driver. Eventually the driver will need to respond to the preference pane, returning small structures of data. In both cases, what IPC would you recommend?

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Re: Modifying Bundle's Info Property List
by Sean Morrell 21 Nov '01

21 Nov '01

ssudre(a)intego.com writes: >On mercredi, novembre 21, 2001, at 04:33 , Sean Morrell wrote: > >> I don't know which conference these questions are best suited. Please >> tell me if this message needs to be redirected. I'm using the Core >> Foundation Bundle services to obtain the information property list for a >> driver bundle using the routine CFBundleGetInfoDictionary. However this >> routine returns an immutable reference and I need to modify this >> information property list. How can I modify the information property >> list >> for the bundle? > >CFMutableDictionaryRef CFDictionaryCreateMutableCopy(CFAllocatorRef >allocator, CFIndex capacity, CFDictionaryRef theDict); I may be approaching this wrong. Actually, I don't want a copy. I need to change the property list file itself. How can this be done? > > >For more information, you can have a look at the CFDictionary.h header. > >> Also since the bundle is a driver and will reside in >> /System/Library/Extensions, will I have a file access issue? > >Wouldn't it be possible to add it to the /Library/Extensions folder >instead ? (I don't know if it would work). Hummmm ... I hadn't really thought about it. That's probably where third party drivers should reside. Thanks. > > >> The property >> list is being modified from a system preference pane in user space. How >> do I get the necessary access? > >With the Security Framework. >_______________________________________________ >darwin-kernel mailing list >darwin-kernel(a)lists.apple.com >http://www.lists.apple.com/mailman/listinfo/darwin-kernel

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