August 2012 - Darwin-kernel

getpwnam("") && getgrnam("") returns an found entry but not NULL on Mountain Lion
by Reeze Xia 10 Aug '12

10 Aug '12

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Re: getpwnam("") && getgrnam("") returns an found entry but not NULL, is it a bug?
by Stephen Checkoway 10 Aug '12

10 Aug '12

On Aug 9, 2012, at 11:40 PM, Reeze Xia wrote: > I don't know if this is the right mailing list to post, if not please forgive me plz :) I think darwin-dev would be more appropriate. > The below is reproducible code. > #include <stdio.h> > #include <sys/types.h> > #include <pwd.h> > #include <unistd.h> > #include <stdlib.h> I think this should be #include <stdio.h> #include <grp.h> > Expected Results: > Right > > Actual Results: > Found empty group I can't confirm your results on ML as I haven't "upgraded" but it certainly seems to do the right thing on Snow Leopard. -- Stephen Checkoway _______________________________________________ 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: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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getpwnam("") && getgrnam("") returns an found entry but not NULL, is it a bug?
by Reeze Xia 10 Aug '12

10 Aug '12

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Re: Kernel crash on mac os x <= 10.6.8
by William Kucharski 08 Aug '12

08 Aug '12

Unless things have changed, you never used to be able to view RADAR bug reports other than your own. -- William Kucharski _______________________________________________ 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: https://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: Kernel crash on mac os x <= 10.6.8
by Stan Sieler 08 Aug '12

08 Aug '12

Re: On Aug 8, 2012, at 5:44 AM, Antoine Missout wrote: > Found a second, different bug that will crash the kernel on any mac os x >= 10.6.0, including Mountain Lion. > > Again, using a hand-crafted mach-o file. > > rdar://12055373 Sorry to waste bandwidth on this if it's in a FAQ... On my Mac Pro (Snow Leopard), if I click on "rdar://12055373" in Mac Mail, it tries to launch "Mobile Safari" which crashes (report at end of this email). If I enter: rdar://12055373 into Safari on my iPad (hey, that's "mobile"?), I'm first prompted to logon with my Apple ID ... and then am told "You do not have privileges to view problemID 12055373". If I enter it into (normal) Safari on my Mac, I get a window with the same crash. If I enter it into (normal) Safari in a (virtual) Lion, I get "Safari ... doesn't recognize internet addresses beginning with rdar:". So, how does one use such a link successfully? thanks, Stan ------------------------------------------ crash report: Process: MobileSafari [23765] Path: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.1.sdk/Applications/MobileSafari.app/MobileSafari Identifier: com.apple.mobilesafari Version: ??? (???) Code Type: X86 (Native) Parent Process: launchd [97] Date/Time: 2012-08-08 10:48:49.772 -0700 OS Version: Mac OS X 10.6.8 (10K549) Report Version: 6 Interval Since Last Report: 587412 sec Crashes Since Last Report: 4 Per-App Crashes Since Last Report: 4 Anonymous UUID: 884E879F-FC29-4222-B2F5-64EB4C6D59F2 Exception Type: EXC_BREAKPOINT (SIGTRAP) Exception Codes: 0x0000000000000002, 0x0000000000000000 Crashed Thread: 0 Dyld Error Message: Library not loaded: /System/Library/PrivateFrameworks/GraphicsServices.framework/GraphicsServices Referenced from: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.1.sdk/Applications/MobileSafari.app/MobileSafari Reason: image not found _______________________________________________ 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: https://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: I/O Scheduler
by Ken Hornstein 08 Aug '12

08 Aug '12

>Maybe someone more knowledgeable can point out where in the VFS/UBC >system the request combining happens - all I can say is I've certainly >seen it in action from the requests it generates. There is also >speculative read-ahead that causes I/O request sizes to grow >exponentially when you read large files sequentially, which is >presumably done in the same place. (you can easily observe this in >action using dd and a filter scheme driver that logs requests) I _think_ this happens in one of the cluster_* routines. I'd have to check to be sure. --Ken _______________________________________________ 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: https://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: I/O Scheduler
by Phil Jordan 08 Aug '12

08 Aug '12

Hi Alistair On Wed, Aug 8, 2012 at 1:44 PM, Alistair Lynn <arplynn(a)gmail.com> wrote: > I've been digging about a little, but to no avail. Whereabouts in the kernel might I find the I/O scheduler? I assume you mean disk I/O scheduling? It's a bit dated, but Amit Singh's Mac OS X Internals book mentions that there is no explicit disk scheduler in OSX. (p. 1366) Quote: Note that Mac OS X does not use explicit disk scheduling. In particular, I/O requests are not explicitly reordered, although the non-I/O Kit parts of the kernel may defer a request in order to combine several requests into a single large request. To the best of my knowledge, nothing has changed about this since 10.4, which was the latest version at the time the book was published. Maybe someone more knowledgeable can point out where in the VFS/UBC system the request combining happens - all I can say is I've certainly seen it in action from the requests it generates. There is also speculative read-ahead that causes I/O request sizes to grow exponentially when you read large files sequentially, which is presumably done in the same place. (you can easily observe this in action using dd and a filter scheme driver that logs requests) The IOBlockStorageDriver class (much further down the stack) does handle request deblocking, that is, ensuring that requests are aligned to sector boundaries, and splitting them so they don't exceed hardware limits for maximum request size etc. but that's not really scheduling as such. I suspect the reason why Apple never bothered to implement a scheduler might be that storage devices these days have hardware support for scheduling requests (SATA NCQ/SCSI TCQ) anyway, and requests to solid-state storage don't need scheduling anyway. The storage stack also doesn't support insertion of barriers, which would make reordering dangerous. (IOStorage::synchronizeCache() essentially acts as a crude barrier, though its semantics are a little fuzzy - see darwin-drivers/darwin-kernel list archives from many years ago for details) As a comparison, Linux actually disables its I/O scheduler on devices which support NCQ/TCQ. I think it does the same for non-rotational devices. Hope that helps (and I hope I got all of the above right) phil _______________________________________________ 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: https://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: Kernel crash on mac os x <= 10.6.8
by Antoine Missout 08 Aug '12

08 Aug '12

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I/O Scheduler
by Alistair Lynn 08 Aug '12

08 Aug '12

Hi all- I've been digging about a little, but to no avail. Whereabouts in the kernel might I find the I/O scheduler? Alistair _______________________________________________ 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: https://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: Kernel crash on mac os x <= 10.6.8
by Phil Jordan 08 Aug '12

08 Aug '12

On Wed, Aug 8, 2012 at 11:06 AM, Per Mildner <Per.Mildner(a)sics.se> wrote: > On Aug 8, 2012, at 10:39 AM, Antoine Missout wrote: > >> Thanks Andrew. >> >> rdar://12054362 > > Since the Apple bug database is not public (a.k.a. "a faceless blackbox") you may consider adding the defect in the Open Radar database at http://openradar.appspot.com/. That's probably not a great idea for a bug that has security implications. (that said, I'm not trying to kick off a full disclosure debate on this list) phil _______________________________________________ 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: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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