Re: [uClinux-dev] segmentation fault while starting user-program under heavy interrupt load
Hi Juergen, Juergen Pfeiffer wrote: Greg Ungerer schrieb: This is on Freescales code base on the 5485 right? (That is an old kernel...) Yes it is. Lots of interrupts means lots of context switches, into and out of the kernel. If there is any bugs in the entry or exit code that interferes with the running application processes then you can get application crashes like you see. Of course i looked at the kmalloc()'s in my driver, but there are only very few. They are only called on driver driver initialisation. I could see no obvious problems yet with the allocated memory. Much more likely to be related to the interrupt/softirq load, and kernel code related to processing that. Di you have any idea, how i can proof or falsify, if the problem is in my driver or if it is in general kernel code of interrupt/softirq processing? If you can make your driver do most of its work without interrupts then that would go part of the way. Obviously this is to test, performance won't matter, poll to IO if you can. Rule our the raw access (memory/bus cycle corruption, etc). Regards Greg Greg Ungerer -- Chief Software Dude EMAIL: [EMAIL PROTECTED] Secure Computing CorporationPHONE: +61 7 3435 2888 825 Stanley St, FAX: +61 7 3891 3630 Woolloongabba, QLD, 4102, Australia WEB: http://www.SnapGear.com ___ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
Re: [uClinux-dev] segmentation fault while starting user-program under heavy interrupt load
Hi Greg Greg Ungerer schrieb: > > This is on Freescales code base on the 5485 right? > (That is an old kernel...) > Yes it is. > > Lots of interrupts means lots of context switches, into and out > of the kernel. If there is any bugs in the entry or exit code > that interferes with the running application processes then > you can get application crashes like you see. > > >> Of course i looked at the kmalloc()'s in my driver, but there are >> only very few. They are only called on driver driver initialisation. >> I could see no obvious problems yet with the allocated memory. > > Much more likely to be related to the interrupt/softirq load, and > kernel code related to processing that. Di you have any idea, how i can proof or falsify, if the problem is in my driver or if it is in general kernel code of interrupt/softirq processing? Regards -- Jürgen Pfeiffer * _mailto:[EMAIL PROTECTED] SesKion Softwareentwicklung und System Konzeption GmbH ( : +49-711-9905814 Karlsruher Str. 11/1 Fax: +49-711-9905827 70771 Leinfelden-Echterdingen 1 _http://www.seskion.de_ Vertretungsberechtigte Geschäftsführer: Gerhard Kuhn, Jürgen Pfeiffer, Horst Tabel. Handelsregister: HRB 224379 Amtsgericht Stuttgart Unsere Ust-IdNr.: DE189769369 Unsere Steuernummer: 99060 / 04155 ___ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
Re: [uClinux-dev] segmentation fault while starting user-program under heavy interrupt load
Gavin Lambert schrieb: > On !MMU systems there is no memory protection between processes or between > kernel and user space. So if a driver is randomly stomping over memory > supposedly in user space then it will break things. Another possibility is > just that you're running out of RAM, or that it's becoming too fragmented, > since kernel and userspace use the same memory pools. > Hi Gavin The Coldfire MCF5485 has a builtin MMU and it is used by the linux implementatio i use. So maybe uClinux is not the correct mailing list. Sorry. Is there a mailing list for embedded linux? -- Jürgen Pfeiffer * _mailto:[EMAIL PROTECTED] SesKion Softwareentwicklung und System Konzeption GmbH ( : +49-711-9905814 Karlsruher Str. 11/1 Fax: +49-711-9905827 70771 Leinfelden-Echterdingen 1 _http://www.seskion.de_ Vertretungsberechtigte Geschäftsführer: Gerhard Kuhn, Jürgen Pfeiffer, Horst Tabel. Handelsregister: HRB 224379 Amtsgericht Stuttgart Unsere Ust-IdNr.: DE189769369 Unsere Steuernummer: 99060 / 04155 ___ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
Re: [uClinux-dev] segmentation fault while starting user-program under heavy interrupt load
Greg Ungerer wrote: Hi Huergen, ^^^ Oops, typo, sorry Juergen :-) Regards Greg Juergen Pfeiffer wrote: I'm using Linux Kernel 2.6.10 for Coldfire 5485 in an embedded application. I developped my own device-driver (Profibus), working on the internal UART of the coldfire. This is on Freescales code base on the 5485 right? (That is an old kernel...) This Driver produces heavy hard-interrupt und soft-irq load, because UART Data is received and transmitted with 93750 bit/s. But the driver works fine and communicates with other devices as it should do. No Kernel-oops. Now i have the situation, that when i try to start some user program like "ls" or "ps" ... out of an interactive bash, sometimes i get a message "Segmentation fault" and the program isn't started. Then i try again and this time it works. This shows up in any standard user programm (most of them inside busybox), but it happens only about every 100th try. free shows over 1 Megabyte of free memory. I cannot believe, that the problem is in all of the user programms. I deactivated my driver and (bad world) no problem anymore. So my question is: How can an error inside a device driver produce problems in starting user programs? Lots of interrupts means lots of context switches, into and out of the kernel. If there is any bugs in the entry or exit code that interferes with the running application processes then you can get application crashes like you see. Of course i looked at the kmalloc()'s in my driver, but there are only very few. They are only called on driver driver initialisation. I could see no obvious problems yet with the allocated memory. Much more likely to be related to the interrupt/softirq load, and kernel code related to processing that. Regards Greg Hope, somebody can help me -- Jürgen Pfeiffer * _mailto:[EMAIL PROTECTED] SesKion Softwareentwicklung und System Konzeption GmbH ( : +49-711-9905814 Karlsruher Str. 11/1 Fax: +49-711-9905827 70771 Leinfelden-Echterdingen 1 _http://www.seskion.de_ Vertretungsberechtigte Geschäftsführer: Gerhard Kuhn, Jürgen Pfeiffer, Horst Tabel. Handelsregister: HRB 224379 Amtsgericht Stuttgart Unsere Ust-IdNr.: DE189769369 Unsere Steuernummer: 99060 / 04155 ___ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev -- Greg Ungerer -- Chief Software Dude EMAIL: [EMAIL PROTECTED] Secure Computing CorporationPHONE: +61 7 3435 2888 825 Stanley St, FAX: +61 7 3891 3630 Woolloongabba, QLD, 4102, Australia WEB: http://www.SnapGear.com ___ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
Re: [uClinux-dev] segmentation fault while starting user-program under heavy interrupt load
Hi Huergen, Juergen Pfeiffer wrote: I'm using Linux Kernel 2.6.10 for Coldfire 5485 in an embedded application. I developped my own device-driver (Profibus), working on the internal UART of the coldfire. This is on Freescales code base on the 5485 right? (That is an old kernel...) This Driver produces heavy hard-interrupt und soft-irq load, because UART Data is received and transmitted with 93750 bit/s. But the driver works fine and communicates with other devices as it should do. No Kernel-oops. Now i have the situation, that when i try to start some user program like "ls" or "ps" ... out of an interactive bash, sometimes i get a message "Segmentation fault" and the program isn't started. Then i try again and this time it works. This shows up in any standard user programm (most of them inside busybox), but it happens only about every 100th try. free shows over 1 Megabyte of free memory. I cannot believe, that the problem is in all of the user programms. I deactivated my driver and (bad world) no problem anymore. So my question is: How can an error inside a device driver produce problems in starting user programs? Lots of interrupts means lots of context switches, into and out of the kernel. If there is any bugs in the entry or exit code that interferes with the running application processes then you can get application crashes like you see. Of course i looked at the kmalloc()'s in my driver, but there are only very few. They are only called on driver driver initialisation. I could see no obvious problems yet with the allocated memory. Much more likely to be related to the interrupt/softirq load, and kernel code related to processing that. Regards Greg Hope, somebody can help me -- Jürgen Pfeiffer * _mailto:[EMAIL PROTECTED] SesKion Softwareentwicklung und System Konzeption GmbH ( : +49-711-9905814 Karlsruher Str. 11/1 Fax: +49-711-9905827 70771 Leinfelden-Echterdingen 1 _http://www.seskion.de_ Vertretungsberechtigte Geschäftsführer: Gerhard Kuhn, Jürgen Pfeiffer, Horst Tabel. Handelsregister: HRB 224379 Amtsgericht Stuttgart Unsere Ust-IdNr.: DE189769369 Unsere Steuernummer: 99060 / 04155 ___ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev -- Greg Ungerer -- Chief Software Dude EMAIL: [EMAIL PROTECTED] Secure Computing CorporationPHONE: +61 7 3435 2888 825 Stanley St, FAX: +61 7 3891 3630 Woolloongabba, QLD, 4102, Australia WEB: http://www.SnapGear.com ___ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
RE: [uClinux-dev] segmentation fault while starting user-program under heavy interrupt load
Quoth Juergen Pfeiffer: >I'm using Linux Kernel 2.6.10 for Coldfire 5485 in an embedded >application. >I developped my own device-driver (Profibus), working on the internal >UART of the coldfire. [...] Now i have the situation, that when i try to start some user program like >"ls" or "ps" ... out of an interactive bash, sometimes i get a message >"Segmentation fault" and the program isn't started. Then i try again and >this time it works. [...] >I deactivated my driver and (bad world) no problem anymore. > >So my question is: >How can an error inside a device driver produce problems in starting >user programs? On !MMU systems there is no memory protection between processes or between kernel and user space. So if a driver is randomly stomping over memory supposedly in user space then it will break things. Another possibility is just that you're running out of RAM, or that it's becoming too fragmented, since kernel and userspace use the same memory pools. You'll need to carefully go over the code in your driver, looking not just at the allocations, but also the deallocations and use of pointers. In particular look for cases where you're potentially accessing a pointer after it has been deallocated, or accessing beyond the bounds of a buffer allocation. Also watch out for race conditions and similar concurrency issues (remember that the kernel is potentially reentrant in many places). ___ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
