June 2007 - Darwin-kernel - lists.apple.com

Re: How to detect Mac OS X version from a kext
by Michael Smith 17 Jun '07

17 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Jun 16, 2007, at 11:27 PM, Bhavesh Davda wrote: I really want to know what I asked. I've been told by someone that attended WWDC that a bug I had reported in the Tiger kernel has finally been fixed in the latest Leopard seed, and the workaround I had put in my kext is no longer needed. Instead of spinning 2 different versions of the kext, one for Tiger and one for Leopard, I would like to figure out at runtime whether I need to do the workaround or not, and just have one version of the kext. That sounds eminently desirable. This is a marketing number. = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… So no, you don't want to know whether you are running on Tiger or not. What you want to know is whether or not you are linked with a kernel that has the bug you're working around or not. Irritatingly, the thing that you most want - the kmod version for the symbol set(s) against which you are matched - is not easy to get. The kmod_info struct that is passed to your kmod_start routine contains a list of kmod references which would include the kernel symbol sets against which you're linked, but if you're an I/O Kit kext I don't think this is readily available because Xcode is generating this function for you magically behind the scenes. (Am I missing something here, folks? I couldn't find a public interface to fetch the kmod_info data except via invoking kextstat, which doesn't work well for kernel mode consumers...) I don't know what versioning scheme Apple uses for the OS (10.4.9) versus the xnu kernel (792.18.5) This is related to build and branch activity within the development organisation. versus the utsname (8.9.1). Hence the question. This number is your best bet; the major digit has consistenly been bumped at each major OS release. You will want to get confirmation from DTS (Garth?), but it seems reasonable to assume that as Panther was 7.x and Tiger was 8.x that Leopard will be 9.x. Assuming you don't care about folks running old Leopard kernels (prior to the fix), then that's easy enough to implement. This email sent to site_archiver(a)lists.apple.com

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Re: Using KAuth for Monitoring File Operations
by Graham J Lee 17 Jun '07

17 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On 15 Jun 2007, at 20:12, Allen Briggs wrote: I did a little more thinking about the implementation, and it would be very hard for the kernel to offer a service that fully facilitates what Yogesh is trying to do without special-casing a lot of things. Does OS X allow layered file systems? It seems like it could be done by an intermediate file system. *furtle* http://developer.apple.com/qa/qa2001/qa1242.html Cheers, Graham. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… On Fri, Jun 15, 2007 at 10:59:07AM -0700, Michael Smith wrote: It does - I remember the Politically Correct File System was demoed a few (like, eight or nine) years ago on Rhapsody. But AFAICR, it's not a supported way of doing business. This email sent to site_archiver(a)lists.apple.com

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Re: How to detect Mac OS X version from a kext
by Bhavesh Davda 17 Jun '07

17 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=JnRIG8pkdDtZTduyq3/LVamJYKNfgQLBXYQc1IhusBwy7DZFZGC+27t6BtlLSjF1lSRTlRKIokrryeIPiGKDeRAOxBlyolYndzD9fRu3VgJUc1apLlnQVn3sktKFaAGoNe6IrPmBlC84ddf1Xpm9x03dvzIiFUuManmwRxgly6Y= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=mcxYQcJxYKZRaRsX1USpm71RcsYzqHt8UF63FXg4hMa4KM4KhAcrkSXxWjw5SfZs7yKKJWYWKBd50GoZHvJV0cvvoycp4U+pQjI4iGOv3cjn38/UZj+8FHUTS4cpllYEUYru73XFO5G8ZFJowXji5yl1ENbWGxXcMv0aEXVTNvg= I really want to know what I asked. I've been told by someone that attended WWDC that a bug I had reported in the Tiger kernel has finally been fixed in the latest Leopard seed, and the workaround I had put in my kext is no longer needed. Instead of spinning 2 different versions of the kext, one for Tiger and one for Leopard, I would like to figure out at runtime whether I need to do the workaround or not, and just have one version of the kext. I don't know what versioning scheme Apple uses for the OS (10.4.9) versus the xnu kernel (792.18.5) versus the utsname (8.9.1). Hence the question. Thanks! - Bhavesh On Jun 16, 2007, at 5:28 PM, Bhavesh Davda wrote: > How do I detect whether a kext is running on 10.4 (Tiger) or 10.5 > (Leopard) programatically? This is almost always the wrong question to be asking; typically you think that you can infer the answer to another question from this one. What is it that you actually want to know? = Mike -- Bhavesh P. Davda _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… On 6/16/07, Michael Smith <drivers(a)mu.org> wrote: This email sent to site_archiver(a)lists.apple.com

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Re: How to detect Mac OS X version from a kext
by Michael Smith 17 Jun '07

17 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Jun 16, 2007, at 5:28 PM, Bhavesh Davda wrote: How do I detect whether a kext is running on 10.4 (Tiger) or 10.5 (Leopard) programatically? What is it that you actually want to know? = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This is almost always the wrong question to be asking; typically you think that you can infer the answer to another question from this one. This email sent to site_archiver(a)lists.apple.com

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Re: How to detect Mac OS X version from a kext
by Waqar Malik 17 Jun '07

17 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:cc:message-id:from:to:in-reply-to:content-type:content-transfer-encoding:mime-version:subject:date:references:x-mailer; b=iRYq58nVEmN+Suq4jTc8fd3FoiM87g3V4fSFPdOPbl6AdGTy+bM4gdXHQtMOVtxc1KRE/KDTCLsb9Hq8JaKL3GYiFgqve9UpGr1rYa543KZCi5TutTDgWEt7RUHYKGcGHX/sA81IVqdwg/QHLAUmudyR+IVnU7tBeAzXoJoJH4o= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:cc:message-id:from:to:in-reply-to:content-type:content-transfer-encoding:mime-version:subject:date:references:x-mailer; b=VU+riyh+TwPOagzPYORWCKXKda0hN1AXGjoXnpVDeYN5PstLYlBs6x6aLHumfsZ/rKRsO/WlRqbuhgS9S+LlwFK1ePIe3kE1dZbYyR3OTGTAGfSHhbLjeuHqnjcV4hIE38Qj7QV93eXyCWjoz+8WjoasgwgJZ5xcOHBxuvsrWpk= sysctl is your friend. kern.osrelease kern.osversion --Waqar On Jun 16, 2007, at 7:28 PM, Bhavesh Davda wrote: How do I detect whether a kext is running on 10.4 (Tiger) or 10.5 (Leopard) programatically? Thanks! -- Bhavesh P. Davda _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/wmalloc%2Blists%40gmai… _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… <http://developer.apple.com/documentation/Darwin/Conceptual/KernelProgrammin… > This email sent to wmalloc+lists(a)gmail.com This email sent to site_archiver(a)lists.apple.com

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Re: How to detect Mac OS X version from a kext
by Greg Miller 17 Jun '07

17 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Domainkey-signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:to:subject:cc:in-reply-to: mime-version:content-type:content-transfer-encoding: content-disposition:references; b=hguKt/e50b9c0gpfgXQcFy58Dvlp3f8voZUGRhU3AvMD+0yNAVFyRRgY8UI79biD8 FkSSFqS2yWukK/fUxxK2g== Check out libkern/version.h. HTH, G~ How do I detect whether a kext is running on 10.4 (Tiger) or 10.5 (Leopard) programatically? Thanks! -- Bhavesh P. Davda _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/jgm%40google.com This email sent to jgm(a)google.com -- Greg Miller jgm(a)google.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… On 6/16/07, Bhavesh Davda <bhavesh.davda(a)gmail.com> wrote: This email sent to site_archiver(a)lists.apple.com

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How to detect Mac OS X version from a kext
by Bhavesh Davda 17 Jun '07

17 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=iQcZP8X0a4W2w7VPgK8Yce41wl349UwDJFP1bKm9YAT5v99n2rb9Cz8PtsaMdq2EsqlgJIssv0Z9b4EIgJfnRlCPmgLVaDQLQnoBMJ1b7OP5SUxFYGXhckTsrr0+m5rKicOI+KGZBx6I9iUOh0AWU4/JJak7f2QonEm8GZpO6ro= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=kbaLpGjQBSRtvacdIkdtu8nOHyHlAo7fIqDcYkpcwKJ6lNPwlk42LixodF7RfgdbS4jdH/7Py/2jn6D1syzB6l0YHToprkIsxrcvN4YUt+zSoV4EzU2CCVxkhsA12ABg1skI+c7anMcC3u3Z2C0agjNjScszlZQrN5rcIQoxLqw= How do I detect whether a kext is running on 10.4 (Tiger) or 10.5 (Leopard) programatically? Thanks! -- Bhavesh P. Davda _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: Using KAuth for Monitoring File Operations
by Terry Lambert 16 Jun '07

16 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com I did a little more thinking about the implementation, and it would be very hard for the kernel to offer a service that fully facilitates what Yogesh is trying to do without special-casing a lot of things. Does OS X allow layered file systems? It seems like it could be done by an intermediate file system. Short answer: -------- Forget it, it's unworkable. Long answer: -------- They are allowed, but they are not supported. -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… On Jun 15, 2007, at 12:12 PM, Allen Briggs wrote: On Fri, Jun 15, 2007 at 10:59:07AM -0700, Michael Smith wrote: In particular, there is no way to have a hook into a transaction such that there are no change until the commit, and you get commit notification (and can do a backup) before any actual change takes place. I think the only way he'll get what he wants, frankly, is to replace HFS completely with an HFS that has these hooks built into it, and is built on a transaction model. The alternative is to back up at every authorization transaction requesting write access in scope VNODE, and then deal with it in scope FILEOP when the modified bit is present (and discard the change if not). You are still potentially shot in the foot, though, for memory mapped files, since the vnode reference is noted at close time rather than 1->0 reference time, so a reference held by the VM system is not going o notify you of pages dirtied as a result of memory mapped operations, if the file is closed after the mapping is established. Again, the only way around this would be to hook the paging path in the FS itself, below the VNOP layer, to get page write notifications, and you're back to replacing HFS. I.e. you can write them, but we will not help you fix them, and if they break, it's on you, and there are known cases where they would break. The primary reason for this is that there is no upcall mechanism in the Heidemann stacking architecture for object aliases. Consider an FS, FS-1, stacked on another FS, FS-2. It does whatever additional things it does, but the key feature it has is that it vends a vnode that refers to the vnode in the underlying FS. Each of these vnodes has an associated UBC structure that refers to the VM object backing the files. Now say you expose both these objects in the name space, either intentionally (by not mounting the second FS over top of the first's mount point) or unintentionally (by having a file open on FS-2 before FS-1 is mounted over top of it). In this case, you have a reference to a vnode vended by the upper layer and a vnode vended by the lower layer, both with buffer cache backing the same range of the file in different pages. Now, if you write using the upper layer vnode, everything is fine, since the put-page operation will go to the upper layer, modify the backing object, and push the change into the lower layer by calling the underlying FSs putpage as well (which would copy the change to the lower layers backing object, as well). Fine and dandy: ineffecient as all get out, but workable. Say, though, that you write to the lower layer vnode; now you push the changes into the lower layer vnoe's backing object, but the upper layer backing object does not get modified; further, there is no back- link to the upper layer vnode from the lower, so the cached data in the upper level vnode backing object becomes stale. Matters are made worse, because the upper level backing object can have a cardinality of N - that is, you could stack N upper level FSs on top of one lower level FS, so even if you had a pointer, there's no way to represent the data relationship to upper level obejcts. FreeBSD, OpenBSD, NetBSD, and DragonFlyBSD's stacking FS framework, which is also out of the BSD-4.4-Lite2 distribution, and so contains the same code out of John Heidemann's Ficus project out of UCLA, all face this same issue. The only real resolution to this is to deunify the VM and buffer cache (which you could do, by forcing the use of direct I/O for all files opened through a stacked FS), or to constrain what you are allowed to stack to only things which do directory folding or other non-block- translation type transforms. In other words, you constrain things so that you directly access the backing object pages from the underlying FS raw, rather than through an upper level alias: this means no compressing FSs, no encrypting FSs, etc., etc.. It's possible to address the constrained set (non-transformational) stacking layers by permitting aliasing of UBC objects and forcing stacking to not expose elsewhere in the namespace (this is essentially how FiST handles stacking), but it's not really clear that this would be as big a win as people seem to think it would be. This email sent to site_archiver(a)lists.apple.com

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Re: Using KAuth for Monitoring File Operations
by Allen Briggs 15 Jun '07

15 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com User-agent: Mutt/1.5.13 (2006-08-11) On Fri, Jun 15, 2007 at 10:59:07AM -0700, Michael Smith wrote: > I did a little more thinking about the implementation, and it would > be very hard for the kernel to offer a service that fully facilitates > what Yogesh is trying to do without special-casing a lot of things. Does OS X allow layered file systems? It seems like it could be done by an intermediate file system. -allen -- Allen Briggs | http://www.ninthwonder.com/~briggs/ | briggs(a)ninthwonder.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: Using KAuth for Monitoring File Operations
by Michael Smith 15 Jun '07

15 Jun '07

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Jun 15, 2007, at 10:40 AM, Amanda Walker wrote: = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… On Jun 15, 2007, at 9:45 AM, Michael Smith wrote: If your product's aim is to have a complete backup copy of everything, then you are better off waiting in the FILEOP scope for last-close notifications with the modified flag set. This gives you both the indication that the file is not being modified, and an indication that it previously has been. Right--but this is doing the copy after each modification (so you'll have it already saved away when the next modification happens), not on-demand just before the change, which is what Yogesh was asking for. Yes - sorry, I should have been more clear. You can get a hook in before the change happens with KAUTH, but you don't have enough information at that point to do anything useful with the file. But you're quite right--if you're willing to do "backup just after each change" instead of "backup just before each change", hooking FILEOP scope in a Kauth module works very well. I did a little more thinking about the implementation, and it would be very hard for the kernel to offer a service that fully facilitates what Yogesh is trying to do without special-casing a lot of things. One principle the kernel tries to adhere to is that individual operations are, as much as possible, agnostic of the wider context in which they are being performed, and it is knowledge of a number of aspects of that context that are required to determine an impending change from "not modified" to "modified". This email sent to site_archiver(a)lists.apple.com

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