February 2003 - Darwin-kernel

Re: Kernel customization.
by Pelle Johansson 07 Feb '03

07 Feb '03

onsdagen den 5 februari 2003 kl 02.26 skrev Mr. Wong: Hello everyone, I recently compiled the Darwin (XNU portion v.6.0) kernel with the help from the users of this newsgroup (thanks!). I would like to take this a step further and actually do some kernel customizations similar to the ones I've done in Linux. For example, I've recompiled the Linux kernel to specifically allow or disallow cd burning capabilities via SCSI emulation support. Another thing I've done in linux is allow IP packet forwarding. The Redhat (7.3) Linux kernel appears to be much easier to handle than the Darwin kernel because there exists GUI and command line utilities built specifically for the purpose of custization. Anyway, my question is this: How does one go about modifying the XNU kernel to achieve such customizations? Is there a GUI or command line utility? What suggestions do you have or what should I watch out for? Any help will be appreciated. Thanks in advance, Matthew K. Wong Well, you got a lot of replies telling you not to, and I agree with them. Most things are turned on by default. IP forwarding certainly is, and AFAIK, cd burning is handled completely by the cd iokit driver, which is a kernel extension (src/live/IOCDStorageFamily in cvs). However, if you really want to do it, what you do is edit the xnu/*/conf/MASTER.ppc files (on ppc, obviously). By modifying the line RELEASE = [...] you can add and remove options. Of course, it's not completely obvious what options are available, you'll have to look around in the files in the conf/ directories to find out. _______________________________________________ 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: Kernel customization.
by Ragnar Sundblad 07 Feb '03

07 Feb '03

And for the non-KEXT example: --On den 4 Feb 2003 17:26:51 -0800 "Mr. Wong" <keilinw(a)hotmail.com> wrote: Another thing I've done in linux is allow IP packet forwarding. You should check out "sysctl" for this one (man sysctl), net.inet.ip.forwarding in this case. As other has said: Things are a little different in darwin, as with most unixes. BTW: on most linuxes you can enable ip forwarding with "echo 1 > /proc/sys/net/ipv4/ip_forward" which does the same as the sysctl above. There could be a /proc filesystem for darwin too, but there currently isn't AFAIK. I personally prefer _not_ have to rebuild my kernel for any purpose at all (and with darwin I don't even have the oh-yeah-must- remember-to-update-lilo problem ;-) (on ppc at least). /ragge _______________________________________________ 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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__APPLE_API_UNSTABLE
by David Blanton 06 Feb '03

06 Feb '03

Found in /usr/include/sys/random.h : #ifdef __APPLE_API_UNSTABLE void read_random(void* buffer, u_int numBytes); #endif /* __APPLE_API_UNSTABLE */ What is __APPLE_API_UNSTABLE all about and why this innocuous looking function? Peace. DB _______________________________________________ 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: Rebooting the victim machine using gdb
by David Blanton 05 Feb '03

05 Feb '03

On 2/4/03 9:46 PM, "Timothy Standing" <tstanding(a)mac.com> wrote: > I am wondering if anyone knows a trick which would allow me to reboot > a machine using gdb. I am thinking of the situation where I am doing > two machine debugging with a development machine and a test machine. > I've finished a debugging cycle and know that the test machine can't > continue running. It would be great to have some trick with gdb > which would allow me to reboot the test machine without getting up, > walking over to the machine and hitting the reset button. Does > anyone know a way to do this? > > Tim Standing, > SoftRAID, LLC > _______________________________________________ > 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. > Move the debug target next to the development machine. That way you can do man reboot without getting up. _______________________________________________ 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: Kernel customization.
by Ethan Clark 05 Feb '03

05 Feb '03

I believe that the Linux kernel configuration utilities you refer to are not RedHat specific (unless RedHat has decided to take it upon themselves to write a LOT of redundant code -- which would not surprise me in the least). The linux kernel source code has a menu-driven customization utility (both CLI and GUI) that comes with it. (If I'm wrong, someone correct me). Anyways, the Darwin kernel is not configurable in the manner that the linux kernel is. There is no GUI or command-line utility available for configuring xnu. xnu (so far as I'm aware) is pretty much "what-you-build-is-what-you-get". Why do you need to "tweak" your kernel in the first place? In linux, that's fairly understandable (though not so much with RedHat's kernel -- it's customized and has practically everything that everyone could want built in, or in module form -- or maybe that's *why* you want to tweak linux...*sigh*...linux...). Anyways, xnu is fairly straightforward -- what you see is what you've got. Hope this answers your questions (though I'm pretty sure it's not the answer you were *hoping* for). Ethan Clark _______________________________________________ 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: Kernel customization.
by Jeff Jenkins 05 Feb '03

05 Feb '03

On Tuesday, February 4, 2003, at 05:26 PM, Mr. Wong wrote: Hello everyone, I recently compiled the Darwin (XNU portion v.6.0) kernel with the help from the users of this newsgroup (thanks!). I would like to take this a step further and actually do some kernel customizations similar to the ones I've done in Linux. For example, I've recompiled the Linux kernel to specifically allow or disallow cd burning capabilities via SCSI emulation support. Another thing I've done in linux is allow IP packet forwarding. The Redhat (7.3) Linux kernel appears to be much easier to handle than the Darwin kernel because there exists GUI and command line utilities built specifically for the purpose of custization. Anyway, my question is this: How does one go about modifying the XNU kernel to achieve such customizations? Is there a GUI or command line utility? What suggestions do you have or what should I watch out for? Any help will be appreciated. Thanks in advance, Matthew K. Wong As a newbie to Darwin myself, the first thing you have to do is come to the realization that Darwin != Linux (the kernel). So, what you did through xconfig/menuconfig, etc, does not hold for Darwin. The Linux kernel and Darwin kernel are, ...one might say, a tad different! : ) (...incoming HUGE over-simplification/description...) Darwin doesn't have the Linux concept of linking all sorts of device modules into the kernel. Darwin has kexts and other similar concepts, but their interaction with the raw kernel is different than what Linux does. This comes down to the monolithic vs. modular OS designs. People can argue the merits of one architecture vs. another, but this isn't really the place for such discussions. Bottom line: you just might have to get down and dirty with Darwin to learn how it works. Or in other words: "...use the source Luke..." : ) There are several good PDF files that ship with the Dev Tools that describe the kernel env as well as discuss the core modules of the kernel (Mach/BSD). -- jrj _______________________________________________ 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: Kernel customization.
by Brian Tabone 05 Feb '03

05 Feb '03

Mr. Wong, Well, things are a bit different in Darwin, and actually easier I think. If you need new kernel functionality, usually you would create/ modify a KEXT (Kernel Extension, similar to loadable modules in Linux, but much more flexible). The nice thing about KEXT's and Darwin is that you need not recompile your kernel to support any new KEXT's. Darwin has a generic kernel module interface which means the kernel does not need functionality for a specific KEXT compiled in (unlike loadable modules in Linux) I believe OS X comes with ATAPI CD burner support built in already, but I'm not 100% sure. As for IP forwarding, all you have to do to turn that on in Darwin is to set net.inet.ip.forwarding to 1. Read the manpage on sysctl for more information. sysctl is similar in some ways to /proc on Linux. Anyhow, a great place to start is : http://developer.apple.com/techpubs/macosx/Darwin/index.html Specifically, 'Kernel Programming', 'Kernel Extensions', and IOKit are pertinent to your questions. -I hope that helps Brian Tabone On Tuesday, February 4, 2003, at 07:26 PM, Mr. Wong wrote: Hello everyone, I recently compiled the Darwin (XNU portion v.6.0) kernel with the help from the users of this newsgroup (thanks!). I would like to take this a step further and actually do some kernel customizations similar to the ones I've done in Linux. For example, I've recompiled the Linux kernel to specifically allow or disallow cd burning capabilities via SCSI emulation support. Another thing I've done in linux is allow IP packet forwarding. The Redhat (7.3) Linux kernel appears to be much easier to handle than the Darwin kernel because there exists GUI and command line utilities built specifically for the purpose of custization. Anyway, my question is this: How does one go about modifying the XNU kernel to achieve such customizations? Is there a GUI or command line utility? What suggestions do you have or what should I watch out for? Any help will be appreciated. Thanks in advance, Matthew K. Wong ----------------------------------------------------------------------- - Tired of spam? Get advanced junk mail protection with MSN 8. _______________________________________________ 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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Rebooting the victim machine using gdb
by Timothy Standing 05 Feb '03

05 Feb '03

I am wondering if anyone knows a trick which would allow me to reboot a machine using gdb. I am thinking of the situation where I am doing two machine debugging with a development machine and a test machine. I've finished a debugging cycle and know that the test machine can't continue running. It would be great to have some trick with gdb which would allow me to reboot the test machine without getting up, walking over to the machine and hitting the reset button. Does anyone know a way to do this? Tim Standing, SoftRAID, LLC _______________________________________________ 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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Kernel customization.
by Mr. Wong 05 Feb '03

05 Feb '03

Hello everyone, I recently compiled the Darwin (XNU portion v.6.0) kernel with the help from the users of this newsgroup (thanks!). I would like to take this a step further and actually do some kernel customizations similar to the ones I've done in Linux. For example, I've recompiled the Linux kernel to specifically allow or disallow cd burning capabilities via SCSI emulation support. Another thing I've done in linux is allow IP packet forwarding. The Redhat (7.3) Linux kernel appears to be much easier to handle than the Darwin kernel because there exists GUI and command line utilities built specifically for the purpose of custization. Anyway, my question is this: How does one go about modifying the XNU kernel to achieve such customizations? Is there a GUI or command line utility? What suggestions do you have or what should I watch out for? Any help will be appreciated. Thanks in advance, Matthew K. Wong ------------------------------------------------------------------------ Tired of spam? Get advanced junk mail protection with MSN 8. _______________________________________________ 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: Kernel -> user boundary
by Umesh Vaishampayan 03 Feb '03

03 Feb '03

On Saturday, February 1, 2003, at 03:39 AM, George Andri wrote: This is now fixed, read below. Umesh Vaishampayan wrote: Why can't you do what you want to do in *your* VOP_INACTIVE? I can't do it in VOP_INACTIVE because that's (usually) called way later, mostly when we eject the drive. But since this driver is a hot pluggable device, the user can just yank the device out bypassing our filtering. Also that would not get you immediate results. In that case, make sure you flush all the user data from VM page cache and the meta data from the buffer cache and from your inode cache on every close. This will impact the performance but will reduce the risk of file system corruption when the user "yanks the device" without "ejecting" it first . --Umesh -- Umesh Vaishampayan Mac OS X - Kernel _______________________________________________ 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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