March 2004 - Darwin-kernel - lists.apple.com

Re: OF Boot experts please!
by Nikolay Ilduganov 02 Mar '04

02 Mar '04

For the future, dir lists contents of the folder, so dir mac-io/ata-4@1f000/@0:10,\ dir mac-io/ata-4@1f000/@0:10,\\ should be very helpful. On Mon, Mar 01, 2004 at 09:32:48PM -0800, Rob Ballantyne wrote: > Hi All, > > Thanks to everyone who provided some advice. I just > wanted to report back with what seemed to work in the end. > It was a combination of all the different advice I got. > > Recall the partition map: > > ... > 10: BootX (HFS+) > 11: / (root) (UFS) > > The working set of OF variables is: > > boot-device = mac-io/ata-4@1f000/@0:10,\\:tbxi > boot-file = mac-io/ata-4@1f000/@0:11,\\mach_kernel.new > > The odd thing was that boot-file had to be the explicit > device path and none of the device aliases that name the > same device node. > > My guess is due to the fact that OF loads BootX from > partition 10 and BootX then looks at boot-file to find > the kernel. I'm not quite sure why it can't handle > a devalias. > > Thanks again! > > Rob > _______________________________________________ > 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: OF Boot experts please!
by Rob Ballantyne 02 Mar '04

02 Mar '04

Hi All, Thanks to everyone who provided some advice. I just wanted to report back with what seemed to work in the end. It was a combination of all the different advice I got. Recall the partition map: ... 10: BootX (HFS+) 11: / (root) (UFS) The working set of OF variables is: boot-device = mac-io/ata-4@1f000/@0:10,\\:tbxi boot-file = mac-io/ata-4@1f000/@0:11,\\mach_kernel.new The odd thing was that boot-file had to be the explicit device path and none of the device aliases that name the same device node. My guess is due to the fact that OF loads BootX from partition 10 and BootX then looks at boot-file to find the kernel. I'm not quite sure why it can't handle a devalias. Thanks again! Rob _______________________________________________ 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: Switching disks when accessing a filesystem
by Marek Kozubal 01 Mar '04

01 Mar '04

On Fri, 27 Feb 2004, Dave Rehring wrote: > What I want to do is, when the user double-clicks on a file in > FileSystemA/VolumeA that I'm writing is: FYI, you can not tell an fopen() call from POSIX from a double click from the Finder in a VFS file system. > -copy the selected file to a folder pre-selected by the end-user on VolumeB > -have the OS directly access the file on VolumeB as if there was no VolumeA This sounds simular to the null file system. It simply takes one part of the file system, and puts a copy some where else. However, this approch uses a layered file system and Apple hightly suggests not using layered file systems. But it might be worth the risk in it breaking depending on your goals. It's a little tricky to do this since copying an entire file from within a VFS stack can be non-trivial. > >From looking at the WebDAV source in Darwin, it appears that it kind of does > this, except it 'happens' at the wrong spot. It downloads the file into > /tmp, but applications don't directly access it. They still go through the > WebDAV filesystem, which accesses the file in /tmp. I need to instead have > applications directly access the file [so if they double-click on a file > twice, two copies of the file would be in the local folder for example]. You will need to do something simular to webdev in the fact that there's a user daemon doing a lot of the work. > I was thinking of trying to track down the vnode of the file on VolumeB > [after I copy the file from VolumeA to VolumeB] and returning that vnode > instead of one from VolumeA. > > Does this sound like a reasonable thing to do, or would the OS get confused > about this sort of thing? This is a very nullfs like thing to do, you'd cover the real vnode with one from nullfs, and have nullfs redirct the operations to the appropriate file by swaping around vnodes. If you're only planning on supporting HFS/HFS+, I might suggest just copying outright the HFS+ source, convert it to a kext, and make it override the normal HFS+ matching and add whatever bits to make it work there, which would avoid the layering problem. --- Marek Kozubal marek(a)portents.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: Various questions from someone starting out Kern development
by Jim Magee 01 Mar '04

01 Mar '04

On Feb 29, 2004, at 12:24 AM, Rob Ballantyne wrote: > I've looked at some of the doc and read some of the list looking for > various things. I can't find em. I hope the questions are not too > obvious and that I haven't missed finding them somewhere. I'd greatly > appreciate any answers and/or pointers to doc I haven't found yet. These are some pretty good questions for a "newbie." As Justin stated in a related follow-up, some have been answered before. But maybe its time for a little recap anyway. > 1. As I recall Mach based systems are usually a collection of > communicating Mach tasks/servers but it appears that the Darwin/Mac > OS X kernel must be a single monolithic Mach Task. Although there > is no netname server at all, the bootstrap server subsumes these > responsibilities I've read, not even the bootstrap server is > available to the Kernel task(s). So the questions here are: > is the BSD kernel a single Mach task? Are there any other Mach > tasks (doing Mach IPC) within the kernel boundry? Most of the kernel is a single task. There is one "wart"/vestige where there is a second task sharing the address space with the rest of the kernel. That is the BSD code that handles Mach exceptions and turns them into BSD signals. It actually runs in a separate task within the kernel. But, there is little valid reason to do it that way - the added protection is minimal. Mostly, it is driven by the fact that ports are referenced by names in that environment, just like user-space, rather than by pointers to Mach port data structures. Therefore, references to stale names are not as fatal as references to stale pointers. But if you depend upon that, you aren't robust enough to be in the kernel anyway. In the BSD exception handler case, It is just something we haven't gotten around to "fixing" yet. > 2. I've also read in the list that the way to do kernel/userland > boundry crossings with Mach is to somehow pass the required port > rights from userland into the kernel. How is this usually done? > Are there realtivly simple examples of services (Mach servers if > that's possible) living in kernel land that are in the kernel > that someone can point me to? Unless you are making use of an existing interface that passes port rights, its somewhat of a catch-22 situation. IOKit user-clients already do this passing, and so are highly recommended mechanisms for "getting hooked up." Other code, reached through direct system calls, take advantage of a "know fact." All such calls are done in the context of the calling task (using the calling thread - which holds a reference on that task). So, you can just pass a 32-bit value port name and "look up that port name" while in the context of that call to get a send right reference to it using Mach's in-kernel IPC interfaces. Of course, all of Mach's interfaces are SPI in the Mac OS X world, even these in-kernel Mach interfaces for KEXTs. So, anything using them will not get release-to-release binary compatibility they can depend upon. > 3. Older Mach documentation pretty explicitly states that MachIPC is > a wire protocol in addition to an in kernel IPC mechanism. Are the > hooks still in Darwin/Mac OS X to do IPC between distributed > processes? Error recovery in a distributed (over the wire) world is hard. Embedding those semantics into Mach messaging makes it slow(er than it needs to be). Given the wide variety of choices for over-the-wire protocols and their associated error recovery semantics, we felt it wasn't necessary to add yet another - and would only hamper our ability to use Mach IPC in more performance critical ways within a machine. So, one of the first steps for Mac OS X/Darwin was to remove distributed Mach IPC as a part of the supported environment. That doesn't mean that we wouldn't use it "across the wire" in a tightly coupled distributed system/cluster. It's just that we probably would never recommend using it in a loosely coupled environment. --Jim [demime 0.98b removed an attachment of type application/pkcs7-signature which had a name of smime.p7s] _______________________________________________ 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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OF boot-file parameter
by William Kucharski 01 Mar '04

01 Mar '04

The boot-device should automatically be prepended to the boot-file path, so simply setting boot-file to "mach_kernel.new" should work. William Kucharski kucharsk(a)mac.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: what's the replacement of page
by Quinn 01 Mar '04

01 Mar '04

At 1:13 -0800 27/2/04, Ramble Leon wrote: struct page is used very frenqently in linux, i.e, sendpage, readpage, but I cannot find a replacement struct in darwin-kernel, could you guys give me some advice about it? I'm trying to porting a kernel module from linux to darwin, there are some struct need PAGE as member. It seems that this list is short on Linux kernel experts (and my "Understanding the Linux kernel" book is packed away in boxes because I've just moved house). Perhaps if you explain what sendpage, readpage, etc do, we can suggest Darwin equivalents. 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: OF boot experts please!
by Felix Kronlage 01 Mar '04

01 Mar '04

On Sun, Feb 29, 2004 at 04:39:43PM -0800, Rob Ballantyne wrote: > That part works fine though. If boot-file is null everything > boots perfectly well off of mach_kernel. The question is > what to set boot-file to when I want to boot mach_kernel.new > that is sitting beside mach_kernel in the UFS partition? boot-file = hd:10,\mach_kernel.test should do the trick. -fkr -- gpg-fingerprint: 076E 1E87 3E05 1C7F B1A0 8A48 0D31 9BD3 D9AC 74D0 Felix Kronlage | FKR-RIPE | http://www.hazardous.org/fkr/ fkr(a){grummel.net|opendarwin.org} | http://opendarwin.org/~fkr/ [demime 0.98b removed an attachment of type application/pgp-signature] _______________________________________________ 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: OF boot experts please!
by Rob Ballantyne 01 Mar '04

01 Mar '04

Felix Kronlage wrote: On Sun, Feb 29, 2004 at 03:36:11PM -0800, Rob Ballantyne wrote: boot-device = mac-io/ata-4@1f000/@0,10,\\:tbxi 9: Mac OS 9.2 on Apple_HFS 10: BootX on Apple_Boot 11: / on Apple_UFS wouldn't it be mac-io/ata-4@1f000/@0:10,\\tbxi ? Yes, of course, I miss copied from one computer to another. I double checked and boot-device = mac-io/ata-4@1f000/@0:10,\\:tbxi That part works fine though. If boot-file is null everything boots perfectly well off of mach_kernel. The question is what to set boot-file to when I want to boot mach_kernel.new that is sitting beside mach_kernel in the UFS partition? Thanks, Rob -fkr _______________________________________________ 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: OF boot experts please!
by Felix Kronlage 01 Mar '04

01 Mar '04

On Sun, Feb 29, 2004 at 03:36:11PM -0800, Rob Ballantyne wrote: > boot-device = mac-io/ata-4@1f000/@0,10,\\:tbxi > 9: Mac OS 9.2 on Apple_HFS > 10: BootX on Apple_Boot > 11: / on Apple_UFS wouldn't it be mac-io/ata-4@1f000/@0:10,\\tbxi ? -fkr -- gpg-fingerprint: 076E 1E87 3E05 1C7F B1A0 8A48 0D31 9BD3 D9AC 74D0 Felix Kronlage | FKR-RIPE | http://www.hazardous.org/fkr/ fkr(a){grummel.net|opendarwin.org} | http://www.opendarwin.org/~fkr/ [demime 0.98b removed an attachment of type application/pgp-signature] _______________________________________________ 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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