March 2008 - Darwin-kernel - lists.apple.com

Memory Mapping examples/documentation?
by Greg 03 Mar '08

03 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Based on this I have two questions: Many thanks for any assistance, - Greg _______________________________________________ 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.… Hi, I'm searching for documentation or examples on how to transfer data from a kernel extension written in C to a user-space program. Currently I am using kernel controls to do this, but I would prefer to do this using memory mapping as I feel it would be more efficient, and I think would also simplify my code. I've seen one example that uses IOConnectMapMemory in a user-space C program to connect to an IOKit kernel extension written (obviously) in C++. That kernel extension creates an IODataQueue and uses it as shared memory. 1) Can I convert my C kernel extension (of the Name_start/Name_stop kind) directly to C++ (by simply changing its file-extension) so that I can use the IODataQueue? 2) Since I'm guessing the answer to #1 is probably "no", then are there any examples of how to do something like this in a C-based kernel extension? Or any documentation? I do not want to make my kernel extension an IOKit extension. I'd like to put/copy data into this shared memory, and upon doing so have the user-space program be notified of the new data so that it can be immediately used/copied. This email sent to site_archiver(a)lists.apple.com

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Re: ulimit stack information
by Michael Smith 02 Mar '08

02 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Mar 2, 2008, at 1:15 PM, Ken Mankoff wrote: Ken, = 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.… OK thank you all for the feedback. We haven't actually run into a 64MB limit but are concerned we might. It sounds unlikely based on the Oracle comments, but I think I have a pretty good idea of how to approach it should we require more. Best of luck, and if you find you can't solve your problem due to this sort of system limit, please consider filing a bug. 8) This email sent to site_archiver(a)lists.apple.com

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Re: ulimit stack information
by Ken Mankoff 02 Mar '08

02 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com User-agent: Alpine 1.00 (OSX 882 2007-12-20) That is because of me. Consider fixing your code. -k. _______________________________________________ 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 Sun, 2 Mar 2008, Terry Lambert wrote: On Mar 1, 2008, at 1:57 PM, Ken Mankoff <mankoff(a)gmail.com> wrote: On Sat, 1 Mar 2008, Michael Smith wrote: On Mar 1, 2008, at 11:20 AM, Ken Mankoff wrote: I'm running out of stack space with an application I need to run. I have "ulimit -s 64000" in my .bash_profile. The highest value I can set is 65532. At 65533 it reports, "/usr/bin/ulimit: line 4: ulimit: stack size: cannot modify limit: Invalid argument" I read somewhere that the kernel limits it to 64MB. I figure this is the right place to get a definitive answer and further information. Is it 64 really the limit? How would I allow multiple processes to each have 128 or 256MB each? I'm comfortable recompiling a kernel if need be. Thanks for any advice, First suggestion; fix the app so that it uses less than 64MiB of stack. Hard, but realistically that much stack usage points to a design/algorithmic flaw (Resource consumption that scales 1:1 with some aspect of your dataset directly constrains the dataset that you can manage vs. the availability of the resource in question.) I can't do this. This is 100 000 + lines that is a global climate model. Second suggestion: you have hit the hard limit; you need to be root to increase it. You can either run the shell as root, or write a setuid root wrapper for your application that uses setrlimit(2) to bump both the hard and soft limits up before starting the application. I tried the 'ulimit' command w/ sudo. Won't go above 65532. Even with OK thank you all for the feedback. We haven't actually run into a 64MB limit but are concerned we might. It sounds unlikely based on the Oracle comments, but I think I have a pretty good idea of how to approach it should we require more. This email sent to site_archiver(a)lists.apple.com

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Re: ulimit stack information
by Terry Lambert 02 Mar '08

02 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Mar 1, 2008, at 1:57 PM, Ken Mankoff <mankoff(a)gmail.com> wrote: On Mar 1, 2008, at 11:20 AM, Ken Mankoff wrote: That is because of me. Consider fixing your code. -- 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 Sat, 1 Mar 2008, Michael Smith wrote: I'm running out of stack space with an application I need to run. I have "ulimit -s 64000" in my .bash_profile. The highest value I can set is 65532. At 65533 it reports, "/usr/bin/ulimit: line 4: ulimit: stack size: cannot modify limit: Invalid argument" I read somewhere that the kernel limits it to 64MB. I figure this is the right place to get a definitive answer and further information. Is it 64 really the limit? How would I allow multiple processes to each have 128 or 256MB each? I'm comfortable recompiling a kernel if need be. Thanks for any advice, First suggestion; fix the app so that it uses less than 64MiB of stack. Hard, but realistically that much stack usage points to a design/algorithmic flaw (Resource consumption that scales 1:1 with some aspect of your dataset directly constrains the dataset that you can manage vs. the availability of the resource in question.) I can't do this. This is 100 000 + lines that is a global climate model. Second suggestion: you have hit the hard limit; you need to be root to increase it. You can either run the shell as root, or write a setuid root wrapper for your application that uses setrlimit(2) to bump both the hard and soft limits up before starting the application. I tried the 'ulimit' command w/ sudo. Won't go above 65532. Even with This email sent to site_archiver(a)lists.apple.com

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Re: ulimit stack information
by Terry Lambert 02 Mar '08

02 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com -- Terry On Mar 1, 2008, at 9:53 PM, Michael Smith <drivers(a)mu.org> wrote: On Mar 1, 2008, at 1:57 PM, Ken Mankoff 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/tlambert%40apple.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.… It's that large for Oracle. If you need it bigger, you will need to hack like Michael says. First suggestion; fix the app so that it uses less than 64MiB of stack. Hard, but realistically that much stack usage points to a design/algorithmic flaw (Resource consumption that scales 1:1 with some aspect of your dataset directly constrains the dataset that you can manage vs. the availability of the resource in question.) I can't do this. This is 100 000 + lines that is a global climate model. You should nevertheless propagate the issue back to the developer (s). It's worst with "scientific" code (I speak from personal experience) but the long-term consequences aren't so great either. Second suggestion: you have hit the hard limit; you need to be root to increase it. You can either run the shell as root, or write a setuid root wrapper for your application that uses setrlimit(2) to bump both the hard and soft limits up before starting the application. I tried the 'ulimit' command w/ sudo. Won't go above 65532. Even with "-H". It's not clear to me how you invoked ulimit with sudo, given that it is a shell builtin, but you're right; the kernel constrains the maximum stack to 64MiB via the definition of MAXXSIZ in vmparam.h (I should have tested before replying to you, sorry about that). If you're comfortable rebuilding the Darwin kernel for your system, you might try bumping this up, but it's not clear to me that you won't run into other problems with the process memory map (specifically, I'm not clear on whether there's room for it to be bigger). Another approach you might try is to wrap the top level of your simulation in a pthread and allocate a larger stack for that thread; I'm not certain that this would work either but it wouldn't be terribly difficult to try. This email sent to tlambert(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: ulimit stack information
by Shantonu Sen 02 Mar '08

02 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Shantonu Sent from my MacBook On Mar 1, 2008, at 9:53 PM, Michael Smith wrote: On Mar 1, 2008, at 1:57 PM, Ken Mankoff 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/ssen%40apple.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.… Do you have access to the source of this program? You can relink it with an arbitrarily large stack size. For example: # printf "%x\n" $((512*1024*1024)) 20000000 # cc test.c -Wl,-stack_size,20000000 ld warning: custom stack placement overlaps and will disable shared region # That seems to work for me. If you don't have access to the source, you can probably write a program to rewrite the Mach-O load commands to add a __UNIXSTACK segment and modify the LC_UNIXTHREAD load command First suggestion; fix the app so that it uses less than 64MiB of stack. Hard, but realistically that much stack usage points to a design/algorithmic flaw (Resource consumption that scales 1:1 with some aspect of your dataset directly constrains the dataset that you can manage vs. the availability of the resource in question.) I can't do this. This is 100 000 + lines that is a global climate model. You should nevertheless propagate the issue back to the developer(s). It's worst with "scientific" code (I speak from personal experience) but the long-term consequences aren't so great either. Second suggestion: you have hit the hard limit; you need to be root to increase it. You can either run the shell as root, or write a setuid root wrapper for your application that uses setrlimit(2) to bump both the hard and soft limits up before starting the application. I tried the 'ulimit' command w/ sudo. Won't go above 65532. Even with "-H". It's not clear to me how you invoked ulimit with sudo, given that it is a shell builtin, but you're right; the kernel constrains the maximum stack to 64MiB via the definition of MAXXSIZ in vmparam.h (I should have tested before replying to you, sorry about that). If you're comfortable rebuilding the Darwin kernel for your system, you might try bumping this up, but it's not clear to me that you won't run into other problems with the process memory map (specifically, I'm not clear on whether there's room for it to be bigger). Another approach you might try is to wrap the top level of your simulation in a pthread and allocate a larger stack for that thread; I'm not certain that this would work either but it wouldn't be terribly difficult to try. This email sent to ssen(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: ulimit stack information
by Michael Smith 02 Mar '08

02 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Mar 1, 2008, at 1:57 PM, Ken Mankoff 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.… First suggestion; fix the app so that it uses less than 64MiB of stack. Hard, but realistically that much stack usage points to a design/algorithmic flaw (Resource consumption that scales 1:1 with some aspect of your dataset directly constrains the dataset that you can manage vs. the availability of the resource in question.) I can't do this. This is 100 000 + lines that is a global climate model. You should nevertheless propagate the issue back to the developer(s). It's worst with "scientific" code (I speak from personal experience) but the long-term consequences aren't so great either. Second suggestion: you have hit the hard limit; you need to be root to increase it. You can either run the shell as root, or write a setuid root wrapper for your application that uses setrlimit(2) to bump both the hard and soft limits up before starting the application. I tried the 'ulimit' command w/ sudo. Won't go above 65532. Even with "-H". It's not clear to me how you invoked ulimit with sudo, given that it is a shell builtin, but you're right; the kernel constrains the maximum stack to 64MiB via the definition of MAXXSIZ in vmparam.h (I should have tested before replying to you, sorry about that). If you're comfortable rebuilding the Darwin kernel for your system, you might try bumping this up, but it's not clear to me that you won't run into other problems with the process memory map (specifically, I'm not clear on whether there's room for it to be bigger). Another approach you might try is to wrap the top level of your simulation in a pthread and allocate a larger stack for that thread; I'm not certain that this would work either but it wouldn't be terribly difficult to try. This email sent to site_archiver(a)lists.apple.com

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path length limit in seatbelt/sandbox?
by Michael Weiser 02 Mar '08

02 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com User-agent: Mutt/1.5.16 (2007-06-09) Hello, when trying to compile coreutils-6.10 in a sandbox, I noticed that their getcwd() configure test yielded different results with and without the sandbox. I did some testing and boiled it down to the attached testcase: When a program recursively creates directories, changes into them and calls getcwd(), it can create a rather deep directory structure before failing with error "No such file or directory": michael@esgaroth:~ # ./recgetcwd getcwd: No such file or directory .............................................................................................................................................................................................................................................................. When running the same program in a sandbox that doesn't actualy restrict anything but has a rule containing a path name, it will fail much earlier with "File name too long": michael@esgaroth:~ # sandbox-exec -f recgetcwd.sb ./recgetcwd mkdir: File name too long .............................................................................. Has anyone come across this? -- bye, Micha #include <unistd.h> #include <errno.h> #include <stdio.h> #define TD "recgetcwddir" int main(void) { char *d; int lev = 0; while (1) { printf("."); if (mkdir(TD, 0755)) { perror("mkdir"); break; } if (chdir(TD)) { perror("chdir"); break; } d = getcwd(NULL, 0); if (d == NULL) { perror("getcwd"); break; } free(d); lev++; } printf("\n"); chdir(".."); while (lev >= 0 && !rmdir(TD)) { chdir(".."); lev--; } } (version 1) (allow default) (allow file-read* file-write* (literal "/" ) ) _______________________________________________ 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: ulimit stack information
by Ken Mankoff 01 Mar '08

01 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com User-agent: Alpine 1.00 (OSX 882 2007-12-20) On Mar 1, 2008, at 11:20 AM, Ken Mankoff wrote: On Sat, 1 Mar 2008, Michael Smith wrote: I'm running out of stack space with an application I need to run. I have "ulimit -s 64000" in my .bash_profile. The highest value I can set is 65532. At 65533 it reports, "/usr/bin/ulimit: line 4: ulimit: stack size: cannot modify limit: Invalid argument" I read somewhere that the kernel limits it to 64MB. I figure this is the right place to get a definitive answer and further information. Is it 64 really the limit? How would I allow multiple processes to each have 128 or 256MB each? I'm comfortable recompiling a kernel if need be. Thanks for any advice, First suggestion; fix the app so that it uses less than 64MiB of stack. Hard, but realistically that much stack usage points to a design/algorithmic flaw (Resource consumption that scales 1:1 with some aspect of your dataset directly constrains the dataset that you can manage vs. the availability of the resource in question.) I can't do this. This is 100 000 + lines that is a global climate model. Second suggestion: you have hit the hard limit; you need to be root to increase it. You can either run the shell as root, or write a setuid root wrapper for your application that uses setrlimit(2) to bump both the hard and soft limits up before starting the application. I tried the 'ulimit' command w/ sudo. Won't go above 65532. Even with "-H". _______________________________________________ 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: ulimit stack information
by Michael Smith 01 Mar '08

01 Mar '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Mar 1, 2008, at 11:20 AM, Ken Mankoff 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.… I'm running out of stack space with an application I need to run. I have "ulimit -s 64000" in my .bash_profile. The highest value I can set is 65532. At 65533 it reports, "/usr/bin/ulimit: line 4: ulimit: stack size: cannot modify limit: Invalid argument" I read somewhere that the kernel limits it to 64MB. I figure this is the right place to get a definitive answer and further information. Is it 64 really the limit? How would I allow multiple processes to each have 128 or 256MB each? I'm comfortable recompiling a kernel if need be. Thanks for any advice, First suggestion; fix the app so that it uses less than 64MiB of stack. Hard, but realistically that much stack usage points to a design/algorithmic flaw (Resource consumption that scales 1:1 with some aspect of your dataset directly constrains the dataset that you can manage vs. the availability of the resource in question.) Second suggestion: you have hit the hard limit; you need to be root to increase it. You can either run the shell as root, or write a setuid root wrapper for your application that uses setrlimit(2) to bump both the hard and soft limits up before starting the application. This email sent to site_archiver(a)lists.apple.com

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