June 2002 - Darwin-kernel - lists.apple.com

VFS/user-mode process interaction
by Christopher Taylor 19 Jun '02

19 Jun '02

> My requirement involves a file system (VFS stack implemented as a KEXT) that needs to pass > information off to a Carbon application. What approach would you recommend in that situation? I > currently have the app poll the KEXT, which I dislike in terms of performance and aesthetics, but it > works. Well, one thing you might want to look at is the WebDAV filesystem implementation. It uses socket read/write calls to communicate back and forth between the KEXT and the user-mode application. Now, if Apple would produce a filesystem developer's kit for OS X, that would solve a lot of problems. Yes, I know you can read all sorts of BSD-related books on VFS development, but it would be nice if the bookkeeping could be simplified for developers. For example, a nullfs/user-mode-process pair sample code would be a great help, and working stack examples would be great too. _______________________________________________ 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: Can a kext talk to an application ?
by andrew＠downs.ws 16 Jun '02

16 Jun '02

On Thu, 13 June 2002, Godfrey van der Linden wrote > > At 11:13 -0700 02-6-13, andrew(a)downs.ws wrote: > >I could not find a way to make this type of notification work, so > >instead I used a sysctl with > >polling from the application. The kernel programming doc explains > >sysctl well enough to get started, > >though there were a couple of errors that hopefully have been > >corrected by now. > > I recommend using the UserClient for a blocking work availaible style > API. In general mixing BSD and IOKit can lead to vast complications > with locking. Specifically funnels vs IOWorkLoops. My requirement involves a file system (VFS stack implemented as a KEXT) that needs to pass information off to a Carbon application. What approach would you recommend in that situation? I currently have the app poll the KEXT, which I dislike in terms of performance and aesthetics, but it works. Thanks. Andrew _______________________________________________ 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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How to get rid of "spam" in a Kernel Panic?
by Stéphane Sudre 14 Jun '02

14 Jun '02

In the next release of Mac OS X and so of Darwin, a disclaimer seems to have been added ABOVE the kernel panic information (something like "You need to restart your computer using the power button which is not available on your USB pro keyboard"). It's cool for the user. It's annoying for the developer when you want to have the info of the Kernel Panic. So is there a way to remove this "spam" from a Kernel Panic output (target machine)? _______________________________________________ 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: Can a kext talk to an application ?
by Godfrey van der Linden 13 Jun '02

13 Jun '02

At 11:13 -0700 02-6-13, andrew(a)downs.ws wrote: On Wed, 12 June 2002, darwin-kernel-request(a)lists.apple.com wrote Apple in SimpleUserClient show how to make connections from an application to a kext. But how to do the opposite: sending message from kext to an application ? How to tell the application to do something ? I could not find a way to make this type of notification work, so instead I used a sysctl with polling from the application. The kernel programming doc explains sysctl well enough to get started, though there were a couple of errors that hopefully have been corrected by now. I recommend using the UserClient for a blocking work availaible style API. In general mixing BSD and IOKit can lead to vast complications with locking. Specifically funnels vs IOWorkLoops. Godfrey _______________________________________________ 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: Can a kext talk to an application ?
by andrew＠downs.ws 13 Jun '02

13 Jun '02

On Wed, 12 June 2002, darwin-kernel-request(a)lists.apple.com wrote > Apple in SimpleUserClient show how to make connections from an > application to a kext. > But how to do the opposite: sending message from kext to an application ? > How to tell the application to do something ? I could not find a way to make this type of notification work, so instead I used a sysctl with polling from the application. The kernel programming doc explains sysctl well enough to get started, though there were a couple of errors that hopefully have been corrected by now. Andrew _______________________________________________ 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: IOMemoryCursor segment size issue
by Godfrey van der Linden 13 Jun '02

13 Jun '02

G'day Peter, The problem is that the physical memory you are I/Oing from is fragmented. In X it is very likely that you will always get a maximum physically contiguous I/O of only 4k because that is the page size of the VM system. You have a couple of solutions. 1> Limit your I/Os to 1/2 Meg 2> Or if your DMA engine is capable then my solution is to setup multiple DMA programs then at 'Filter' time (i.e. at primary interrupt time) reprogram the DMA engine with the new DMA. I personally have used approach 2 with really dumb hardware, i.e. no page list at all just a single physical address and length. Using Filter dma chaining I managed to get 112Mb/s throughput with a not bad 5% CPU load. Remember if you go for this solution totally prepare the ENTIRE I/O before starting the first I/O running. There is very little you are allowed to do at primary interrupt time, you certainly CAN NOT call genPhysicalSegments. Godfrey At 16:43 +0100 02-6-13, Peter Young wrote: Hi, I am creating an IOMemoryCursor using: CursP = IOMemoryCursor::withSpecification ( SegFn, UINT_MAX, UINT_MAX, 1 ); which gives me a valid MemoryCursor. I then call CursP->genPhysicalSegments( MemDescP, start, Segments, NumSegments, MaxTransferSize, &BytesToTransfer ); to create the DMA address/len pairs I require in 'Segments'. When I debug SegFn, the Segment.length field is ALWAYS 4096 regardless of the values passed to the withSpecification function above. This gives me a max transfer size of 0.5Mb (128 entries), which is way too small for my requirements. Questions: 1. Why does my segment function ONLY get 4k segments? What am I doing wrong? 2. When 'wiring' the User buffer, do I just need to 'prepare' the MemoryDescriptor, or do I need to 'map' it as well? _______________________________________________ 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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IOMemoryCursor segment size issue
by Peter Young 13 Jun '02

13 Jun '02

Hi, I am creating an IOMemoryCursor using: CursP = IOMemoryCursor::withSpecification ( SegFn, UINT_MAX, UINT_MAX, 1 ); which gives me a valid MemoryCursor. I then call CursP->genPhysicalSegments( MemDescP, start, Segments, NumSegments, MaxTransferSize, &BytesToTransfer ); to create the DMA address/len pairs I require in 'Segments'. When I debug SegFn, the Segment.length field is ALWAYS 4096 regardless of the values passed to the withSpecification function above. This gives me a max transfer size of 0.5Mb (128 entries), which is way too small for my requirements. Questions: 1. Why does my segment function ONLY get 4k segments? What am I doing wrong? 2. When 'wiring' the User buffer, do I just need to 'prepare' the MemoryDescriptor, or do I need to 'map' it as well? Thanks in advance, Peter Young _______________________________________________ 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: Can a kext talk to an application ?
by Stéphane Sudre 12 Jun '02

12 Jun '02

On Wednesday, June 12, 2002, at 01:28 PM, Alain Birtz wrote: Apple in SimpleUserClient show how to make connections from an application to a kext. But how to do the opposite: sending message from kext to an application ? Have a look at the source code for tcplog in the Darwin CVS repository. How to tell the application to do something ? See above. Alternatively, is it possible to (load and) run a shell tool from a kext ? It must be possible but it's far from being a good idea. Can a kext send an AppleEvent to an application ? I don't think it can due to the same restriction that applies to Root boot daemon. _______________________________________________ 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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Can a kext talk to an application ?
by Alain Birtz 12 Jun '02

12 Jun '02

Apple in SimpleUserClient show how to make connections from an application to a kext. But how to do the opposite: sending message from kext to an application ? How to tell the application to do something ? Alternatively, is it possible to (load and) run a shell tool from a kext ? Can a kext send an AppleEvent to an application ? Where can I search about it ? Thank you. _______________________________________________ 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: mach.sym format description
by Justin C. Walker 11 Jun '02

11 Jun '02

On Monday, June 10, 2002, at 05:50 PM, Luke Nihlen wrote: Hi, I'm looking at the mach.sym file and I'm curious about it. How exactly is it used within the kernel, and where could I find some information about it's structure? Does anyone know? I can't find anything on the ADC website. It's not used at all within the kernel. It's the "symbol" part of the kernel that got booted. This simplifies life for users of programs that need to look at kernel data structures. You don't need to know the booted kernel to run those programs. In essence, it's a bunch of stabs: do a 'nm' on it. Regards, Justin -- /~\ The ASCII Justin C. Walker, Curmudgeon-at-Large \ / Ribbon Campaign X Help cure HTML Email / \ _______________________________________________ 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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