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

Re: External Hard Disk Stuff
by Justin Walker 23 May '04

23 May '04

On May 23, 2004, at 11:48, Matt Jaffa wrote: Hi, I am wanting to be able to have access to my external HD by opening it up using something like open(......); and reading the bootsector and switching Sectors around and stuff. My questions might be screwy, but I don't know how to go about doing this, I don't know if I have to write a kernel Extension or if I can do this in User space. Basically I want to mess around with an External HD that is formatted totally in MS-DOS. So what do I need to do to get access to the drive. When I do open(.....) in user space, it says the drive is busy. That is usually an indication that the drive/partition is mounted as a file system. Check with the 'mount' command to see whether this is the case. You should be able to access the "raw" partition if it's unmounted (and file permissions for /dev/whatever are correct). You might want to look at some file system and 'boot' code to see how to interpret the partition data. And yes, you can read and write disk partitions in user mode. Regards, Justin -- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | It's not whether you win or lose... | It's whether *I* win or lose. *--------------------------------------*-------------------------------* _______________________________________________ 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.

1 0

External Hard Disk Stuff
by Matt Jaffa 23 May '04

23 May '04

Hi, I am wanting to be able to have access to my external HD by opening it up using something like open(......); and reading the bootsector and switching Sectors around and stuff. My questions might be screwy, but I don't know how to go about doing this, I don't know if I have to write a kernel Extension or if I can do this in User space. Basically I want to mess around with an External HD that is formatted totally in MS-DOS. So what do I need to do to get access to the drive. When I do open(.....) in user space, it says the drive is busy. Thanks _______________________________________________ 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.

1 0

WWDC 2004 and File System Development
by Quinn 21 May '04

21 May '04

Greetings All If you're developing an external file system for Mac OS X and you'll be attending WWDC 2004, please drop me a line. 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.

1 0

Re: Mach RPCs between user space and a kext
by Sam Vaughan 21 May '04

21 May '04

Wow thanks for all that info Jim. The reason I considered Mach RPC in the first place was that most of the work I wanted to do in my kext was in the Mach part of the kernel. This meant that I had to use Mach search paths and all the appropriate Mach defines to make sure the macros and data structures in the headers were the same in my code as they are in the running kernel. Including BSD headers was pretty much impossible. I realised that I was going to have to put in some BSD code, so I made a separate target in my project to build a BSD library that is then linked in to the kext. That target uses the Kernel.framework search paths like most regular kext targets. Once I had the BSD target, it made sense to take the path of least resistance and publish a sysctl interface. I'm now passing a structure in to the kext via a sysctlbyname call, then doing a copyout of all my data to a user-specified address in the structure. So I've dumped my MIG code for now, but it's good to know it's possible for future reference! Sam On 21/05/2004, at 6:45 AM, Jim Magee wrote: On May 18, 2004, at 9:38 PM, Sam Vaughan wrote: What's not clear to me is how my kext would register the RPC services it provides with the part of the kernel that accepts the calls from user space. There are two methods in which Mach IPC/RPC operates in the kernel. The first method, I'll call it the "active listener method," behaves much like user-state Mach IPC. A kernel thread can wait on a Mach port for a message to arrive, handle it, and reply with a reply message. This method isn't used much in today's kernel (the ux_exception handler thread in BSD behaves this way). The disadvantage of this method is that it requires a thread switch between client and server. But the advantages are that port rights and memory are managed just like at user-space, and it requires "no hookup" into the kernel's IPC object dispatch mechanism. The second method, I'll call it the "passive invocation method," hooks into the middle the Mach IPC implementation for faster (but less "cooked") invocation. Under this method, the Mach IPC implementation determines that the destination is an "IPC kernel object." breaks off its processing of the message just after the "copyin" phase, and invokes the server in the context of the calling thread. As I said, the primary advantage of this method is speed. Only half of a typical IPC operation has been performed (there was a send, but no receive). But for many, the passive nature (tying up and using the user thread to invoke the kernel server) of the call is also an advantage. The disadvantages include having to deal with an "uncooked (e.g. un-received) message. The out-of-line memory is stored in short-hand form (and must be manually "copied-in" to the kernel before you can look at it). The port rights contained in the message are "naked" (i.e. there is no port name, with a set of associated, but managed, rights). Instead, you get a raw pointer to the port and you must manage any rights associated with those ports implicitly. But the biggest disadvantage from your question's perspective is that you must get the port defined as an "IPC kernel object" in the first place. You must "hook it up." There is no mechanism in place for random kernel extensions to "hook up" new IPC kernel objects (they are statically referenced in xnu/osfmk/kern/ipc_kobject.c). So, you must leverage one of the existing IPC kernel objects, or you must use the active listener model. The extensible IPC kernel objects are the IOKit io_connect() and io_service() objects. IOKit provides methods for exporting services using these. But short of using IOKit, there is no way to hook up a "passive" Mach port in a KEXT. That being said - how do you export a port to user-space? Again, IOKit provides a mechanism for doing this (the registry). Also, what port should the user space code use when it issues the RPC? The Kernel Programming doc says to look in bootstrap.h, but this file is empty in Darwin 7.3.0. What they should have said (I haven't looked it up to be sure), is to look in <servers/bootstrap.h>. But these services aren't available IN the kernel, only outside. Can anyone point me to some sample code that uses Mach RPC to cross the user-kernel boundary? The examples in Darwin such as upl_commit_range() and friends simply call Mach from BSD, which isn't really relevant to the issues I'm seeing. Actually, upl_commit_range() is defined in <mach/upl.h> and is published to user-space - although currently unused as a kernel-user boundary interface (until the EMMI gets re-published to user-space, there's not much use for a UPL out there). --Jim _______________________________________________ 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.

1 0

Re: Mach RPCs between user space and a kext
by Jim Magee 20 May '04

20 May '04

On May 18, 2004, at 9:38 PM, Sam Vaughan wrote: > What's not clear to me is how my kext would register the RPC services > it provides with the part of the kernel that accepts the calls from > user space. There are two methods in which Mach IPC/RPC operates in the kernel. The first method, I'll call it the "active listener method," behaves much like user-state Mach IPC. A kernel thread can wait on a Mach port for a message to arrive, handle it, and reply with a reply message. This method isn't used much in today's kernel (the ux_exception handler thread in BSD behaves this way). The disadvantage of this method is that it requires a thread switch between client and server. But the advantages are that port rights and memory are managed just like at user-space, and it requires "no hookup" into the kernel's IPC object dispatch mechanism. The second method, I'll call it the "passive invocation method," hooks into the middle the Mach IPC implementation for faster (but less "cooked") invocation. Under this method, the Mach IPC implementation determines that the destination is an "IPC kernel object." breaks off its processing of the message just after the "copyin" phase, and invokes the server in the context of the calling thread. As I said, the primary advantage of this method is speed. Only half of a typical IPC operation has been performed (there was a send, but no receive). But for many, the passive nature (tying up and using the user thread to invoke the kernel server) of the call is also an advantage. The disadvantages include having to deal with an "uncooked (e.g. un-received) message. The out-of-line memory is stored in short-hand form (and must be manually "copied-in" to the kernel before you can look at it). The port rights contained in the message are "naked" (i.e. there is no port name, with a set of associated, but managed, rights). Instead, you get a raw pointer to the port and you must manage any rights associated with those ports implicitly. But the biggest disadvantage from your question's perspective is that you must get the port defined as an "IPC kernel object" in the first place. You must "hook it up." There is no mechanism in place for random kernel extensions to "hook up" new IPC kernel objects (they are statically referenced in xnu/osfmk/kern/ipc_kobject.c). So, you must leverage one of the existing IPC kernel objects, or you must use the active listener model. The extensible IPC kernel objects are the IOKit io_connect() and io_service() objects. IOKit provides methods for exporting services using these. But short of using IOKit, there is no way to hook up a "passive" Mach port in a KEXT. That being said - how do you export a port to user-space? Again, IOKit provides a mechanism for doing this (the registry). > Also, what port should the user space code use when it issues the RPC? > The Kernel Programming doc says to look in bootstrap.h, but this file > is empty in Darwin 7.3.0. What they should have said (I haven't looked it up to be sure), is to look in <servers/bootstrap.h>. But these services aren't available IN the kernel, only outside. > Can anyone point me to some sample code that uses Mach RPC to cross > the user-kernel boundary? The examples in Darwin such as > upl_commit_range() and friends simply call Mach from BSD, which isn't > really relevant to the issues I'm seeing. Actually, upl_commit_range() is defined in <mach/upl.h> and is published to user-space - although currently unused as a kernel-user boundary interface (until the EMMI gets re-published to user-space, there's not much use for a UPL out there). --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.

1 0

Mach RPCs between user space and a kext
by Sam Vaughan 19 May '04

19 May '04

After weighing up my boundary crossing options for a tool I'm writing, I decided I need to use Mach RPC to talk to my kext from user space. I've read a fair bit about it in the Kernel Programming doc, the Mach 3 Server Writer's Guide and assorted Darwin source code, but what I really need is a very simple example. What's not clear to me is how my kext would register the RPC services it provides with the part of the kernel that accepts the calls from user space. According to the Kernel Programming doc there's no name server for this stuff in MacOS X, and I'm not sure what part of the kernel takes over this responsibility. Also, what port should the user space code use when it issues the RPC? The Kernel Programming doc says to look in bootstrap.h, but this file is empty in Darwin 7.3.0. Can anyone point me to some sample code that uses Mach RPC to cross the user-kernel boundary? The examples in Darwin such as upl_commit_range() and friends simply call Mach from BSD, which isn't really relevant to the issues I'm seeing. Thanks, Sam _______________________________________________ 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.

1 0

Re: Regarding Kernel source
by Olivier Kaloudoff 18 May '04

18 May '04

>1) please consult the archives. This has been asked numerous times on various >darwin related lists at apple >2) at least try to search on the web before asking, since likely you would >find items like this[1] One could search the archives if there was a real useful tool to do so; A search on "proc" gives me 547 responses, for which I get, as a mean of description, the 4 lines of garbage in front of each mail, and no relevant info. http://search.lists.apple.com/darwin-kernel?q=proc&m=all&o=0&wf=200010&wm=s… So, What is actually the best way to look for any information related to os x developpement ? Ask on the mailing list. The mailing lists archives are useless in the current shape. Hey Apple guys, please give us a real tool, or let google do it's work on the mailing lists archives, so that it becames really browsable. Regards, Olivier Kaloudoff LUG Linux Azur France _______________________________________________ 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.

1 0

Re: Regarding Kernel source
by Felix Kronlage 18 May '04

18 May '04

On Tue, May 18, 2004 at 03:35:07PM +0530, Manjunatha N wrote: > I am using Mac OS X 10.3 on PPC G5 dual processor. I want to know about the > structure of the filesystem. > Is it possible to implement a proc file system on Mac which should be similar > to linux proc filesystem? 1) please consult the archives. This has been asked numerous times on various darwin related lists at apple 2) at least try to search on the web before asking, since likely you would find items like this[1] -fkr [1] <url: http://www.kernelthread.com/mac/apme/procfs/> -- 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.

1 0

Re: Regarding Kernel source
by Quinn 18 May '04

18 May '04

At 15:35 +0530 18/5/04, Manjunatha N wrote: I am using Mac OS X 10.3 on PPC G5 dual processor. I want to know about the structure of the filesystem. Is it possible to implement a proc file system on Mac which should be similar to linux proc filesystem? I don't doubt that it's possible (-: Our VFS layer is based on 4.4BSD, which includes a basic procfs. Apple did not pick this up to include in Mac OS X, but there's no reason why you couldn't port it. In fact, it seems that someone has already taken a shot at it. <http://www.kernelthread.com/mac/apme/procfs/> Also i want to know about the boot sequence of Mac. There's a document on our web site that covers this. <http://developer.apple.com/documentation/MacOSX/Conceptual/BPSystemStartup/…> It's very high-level, but it should get you heading in the right direction. There's also a variety of non-Apple resources covering this. For example: <http://www.kernelthread.com/mac/osx/arch_boot.html> 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.

1 0

Regarding Kernel source
by Manjunatha N 18 May '04

18 May '04

hi I am using Mac OS X 10.3 on PPC G5 dual processor. I want to know about the structure of the filesystem. Is it possible to implement a proc file system on Mac which should be similar to linux proc filesystem? Also i want to know about the boot sequence of Mac. Regards Manjunath _______________________________________________ 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.

1 0