* [Xenomai-help] Interrupt numbers @ 2011-12-23 0:38 Terry Fryar 2011-12-23 9:45 ` Gilles Chanteperdrix 0 siblings, 1 reply; 11+ messages in thread From: Terry Fryar @ 2011-12-23 0:38 UTC (permalink / raw) To: xenomai [-- Attachment #1: Type: text/plain, Size: 639 bytes --] Using Xenomai 2.60 with 2.6.38 omap kernel on beagleboard xm. Trying to use a GPIO pin as an interrupt and catch this in a xenomai userspace program. Got the GPIO132 pin set as an input and is working fine. I guess I'll need to set the irq enable register on the omap cpu to enable it to generate irqs. Now...what irq number do I use in the xenomai rt_intr_create() function call?? I'm not sure how the omap gpio interrupts are mapped to the linux kernel/xenomai stuff?? Can I use what's in the arch/arm/plat-omap/include/plat/irqs.h header file? It appears that each bank of GPIO pins has it's own interrupt number?? Thanks! [-- Attachment #2: Type: text/html, Size: 1541 bytes --] ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 0:38 [Xenomai-help] Interrupt numbers Terry Fryar @ 2011-12-23 9:45 ` Gilles Chanteperdrix 2011-12-23 14:04 ` Terry Fryar 2011-12-23 15:26 ` Makarand Pradhan 0 siblings, 2 replies; 11+ messages in thread From: Gilles Chanteperdrix @ 2011-12-23 9:45 UTC (permalink / raw) To: Terry Fryar; +Cc: xenomai On 12/23/2011 01:38 AM, Terry Fryar wrote: > Using Xenomai 2.60 with 2.6.38 omap kernel on beagleboard xm. > > Trying to use a GPIO pin as an interrupt and catch this in a xenomai > userspace program. Got the GPIO132 pin set as an input and is working fine. > I guess I'll need to set the irq enable register on the omap cpu to enable > it to generate irqs. Now...what irq number do I use in the xenomai > rt_intr_create() function call?? I'm not sure how the omap gpio interrupts > are mapped to the linux kernel/xenomai stuff?? Can I use what's in the > arch/arm/plat-omap/include/plat/irqs.h header file? It appears that each > bank of GPIO pins has it's own interrupt number?? Xenomai uses the same interrupt numbers as linux. But rt_intr_create is deprecated in user-space, you should instead write a driver using the rtdm skin. The enable bit is handled by xenomai when you request the irq at xenomai level. -- Gilles. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 9:45 ` Gilles Chanteperdrix @ 2011-12-23 14:04 ` Terry Fryar 2011-12-23 15:26 ` Makarand Pradhan 1 sibling, 0 replies; 11+ messages in thread From: Terry Fryar @ 2011-12-23 14:04 UTC (permalink / raw) To: 'Gilles Chanteperdrix'; +Cc: xenomai Thanks Gilles!! -----Original Message----- From: Gilles Chanteperdrix [mailto:gilles.chanteperdrix@xenomai.org] Sent: Friday, December 23, 2011 3:45 AM To: Terry Fryar Cc: xenomai@xenomai.org Subject: Re: [Xenomai-help] Interrupt numbers On 12/23/2011 01:38 AM, Terry Fryar wrote: > Using Xenomai 2.60 with 2.6.38 omap kernel on beagleboard xm. > > Trying to use a GPIO pin as an interrupt and catch this in a xenomai > userspace program. Got the GPIO132 pin set as an input and is working fine. > I guess I'll need to set the irq enable register on the omap cpu to > enable it to generate irqs. Now...what irq number do I use in the > xenomai > rt_intr_create() function call?? I'm not sure how the omap gpio > interrupts are mapped to the linux kernel/xenomai stuff?? Can I use > what's in the arch/arm/plat-omap/include/plat/irqs.h header file? It > appears that each bank of GPIO pins has it's own interrupt number?? Xenomai uses the same interrupt numbers as linux. But rt_intr_create is deprecated in user-space, you should instead write a driver using the rtdm skin. The enable bit is handled by xenomai when you request the irq at xenomai level. -- Gilles. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 9:45 ` Gilles Chanteperdrix 2011-12-23 14:04 ` Terry Fryar @ 2011-12-23 15:26 ` Makarand Pradhan 2011-12-23 15:53 ` Gilles Chanteperdrix 1 sibling, 1 reply; 11+ messages in thread From: Makarand Pradhan @ 2011-12-23 15:26 UTC (permalink / raw) To: xenomai On 23/12/11 04:45 AM, Gilles Chanteperdrix wrote: > > Xenomai uses the same interrupt numbers as linux. But rt_intr_create is > deprecated in user-space, you should instead write a driver using the > rtdm skin. The enable bit is handled by xenomai when you request the irq > at xenomai level. > Hi Gilles, We use rt_intr_create in our code. So I am trying to understand the reasons for it being deprecated. So far, I have not been able to see any comments in the code regarding the deprecation or anything in the git log. Can you pl comment on the reasons for deprecating rt_intr_create? Will it be removed in the next release? Rgds, Makarand. -- ___________________________________________________________________________ NOTICE OF CONFIDENTIALITY: This e-mail and any attachments may contain confidential and privileged information. If you are not the intended recipient, please notify the sender immediately by return e-mail and delete this e-mail and any copies. Any dissemination or use of this information by a person other than the intended recipient is unauthorized and may be illegal. _____________________________________________________________________ ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 15:26 ` Makarand Pradhan @ 2011-12-23 15:53 ` Gilles Chanteperdrix 2011-12-23 16:16 ` Terry Fryar 2011-12-23 16:17 ` Makarand Pradhan 0 siblings, 2 replies; 11+ messages in thread From: Gilles Chanteperdrix @ 2011-12-23 15:53 UTC (permalink / raw) To: Makarand Pradhan; +Cc: xenomai On 12/23/2011 04:26 PM, Makarand Pradhan wrote: > On 23/12/11 04:45 AM, Gilles Chanteperdrix wrote: >> >> Xenomai uses the same interrupt numbers as linux. But rt_intr_create is >> deprecated in user-space, you should instead write a driver using the >> rtdm skin. The enable bit is handled by xenomai when you request the irq >> at xenomai level. >> > Hi Gilles, > > We use rt_intr_create in our code. So I am trying to understand the > reasons for it being deprecated. So far, I have not been able to see any > comments in the code regarding the deprecation or anything in the git log. Splitting your code between driver and application enforces a clean separation between the two, which helps maintenance, so is good on the long run. > > Can you pl comment on the reasons for deprecating rt_intr_create? Will > it be removed in the next release? We never change ABI in a branch, so, all releases in the 2.6 branch are guaranteed to support the same services as xenomai 2.6.0. But in xenomai 3.0, rt_intr_create will certainly no longer be available. -- Gilles. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 15:53 ` Gilles Chanteperdrix @ 2011-12-23 16:16 ` Terry Fryar 2011-12-23 18:13 ` Philippe Gerum 2011-12-23 16:17 ` Makarand Pradhan 1 sibling, 1 reply; 11+ messages in thread From: Terry Fryar @ 2011-12-23 16:16 UTC (permalink / raw) To: 'Gilles Chanteperdrix', 'Makarand Pradhan'; +Cc: xenomai I would imagine it was nice, however, to have a userspace interrupt ISR so that flaky code could be debugged in userspace before making it into a driver? -----Original Message----- From: xenomai-help-bounces@domain.hid [mailto:xenomai-help-bounces@domain.hid] On Behalf Of Gilles Chanteperdrix Sent: Friday, December 23, 2011 9:53 AM To: Makarand Pradhan Cc: xenomai@xenomai.org Subject: Re: [Xenomai-help] Interrupt numbers On 12/23/2011 04:26 PM, Makarand Pradhan wrote: > On 23/12/11 04:45 AM, Gilles Chanteperdrix wrote: >> >> Xenomai uses the same interrupt numbers as linux. But rt_intr_create >> is deprecated in user-space, you should instead write a driver using >> the rtdm skin. The enable bit is handled by xenomai when you request >> the irq at xenomai level. >> > Hi Gilles, > > We use rt_intr_create in our code. So I am trying to understand the > reasons for it being deprecated. So far, I have not been able to see > any comments in the code regarding the deprecation or anything in the git log. Splitting your code between driver and application enforces a clean separation between the two, which helps maintenance, so is good on the long run. > > Can you pl comment on the reasons for deprecating rt_intr_create? Will > it be removed in the next release? We never change ABI in a branch, so, all releases in the 2.6 branch are guaranteed to support the same services as xenomai 2.6.0. But in xenomai 3.0, rt_intr_create will certainly no longer be available. -- Gilles. _______________________________________________ Xenomai-help mailing list Xenomai-help@domain.hid https://mail.gna.org/listinfo/xenomai-help ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 16:16 ` Terry Fryar @ 2011-12-23 18:13 ` Philippe Gerum 2011-12-23 23:06 ` Terry Fryar 2012-01-19 19:41 ` Michael Pustylnik 0 siblings, 2 replies; 11+ messages in thread From: Philippe Gerum @ 2011-12-23 18:13 UTC (permalink / raw) To: xenomai On 12/23/2011 05:16 PM, Terry Fryar wrote: > I would imagine it was nice, however, to have a userspace interrupt ISR so > that flaky code could be debugged in userspace before making it into a > driver? > Most interrupts are level sensitive these days, which means that you cannot safely step into the code which is supposed to ack the source device using a debugger, your kernel would be stormed by IRQs before you reach the point where the device request is acked. Remember that userland always runs with hw interrupts enabled, regardless of the domain. Even edge triggered IRQs would not give you any guarantee with respect to device timing requirements. GDB aside, also think about a transition to secondary mode for whatever reason while running in userland prior to acking the device: this would be another source of unexpected delays in the acknowledge path. Debugging work is likely to introduce these issues, unless one refrains from using anything else than rt_printf() for logging/observing the runtime state, but that would not help with level sensitive IRQs anyway. You may want to handle the main application logic that responds to an interrupt in userland through, in which case you need some RTDM driver handling the bottom half of real-time interrupts, which would in turn unblock a task sleeping on some read() or ioctl(), to process the event in userland (i.e. UIO-like for real-time IRQs). The bottom line is that you want the IRQ to be acknowledged at device level from kernel space. Keeping it masked in the PIC while transitioning to user-space would be another option, assuming it is not shared with the regular kernel (sharing between rt and non-rt would be just wrong anyway), if the device permits (infinitely) delayed acknowledges, but I would not recommend this. Typically, a user-space code can be wiped off at any time, leaving the device in a weird state. These are the reasons why I have killed the rt_intr_* API in 3.x, it was way too easy to shoot oneself in the foot (and believe me, I saw quite a few damaged feet in the past years due to this issue). What was missing in this API is a clear hint that some user-provided code should live in kernel space to ack each particular device controlled from userland. Using RTDM to implement such code and synchronize with the application logic in userland is a safe, sane and simple solution. > -----Original Message----- > From: xenomai-help-bounces@domain.hid [mailto:xenomai-help-bounces@domain.hid] On > Behalf Of Gilles Chanteperdrix > Sent: Friday, December 23, 2011 9:53 AM > To: Makarand Pradhan > Cc: xenomai@xenomai.org > Subject: Re: [Xenomai-help] Interrupt numbers > > On 12/23/2011 04:26 PM, Makarand Pradhan wrote: >> On 23/12/11 04:45 AM, Gilles Chanteperdrix wrote: >>> >>> Xenomai uses the same interrupt numbers as linux. But rt_intr_create >>> is deprecated in user-space, you should instead write a driver using >>> the rtdm skin. The enable bit is handled by xenomai when you request >>> the irq at xenomai level. >>> >> Hi Gilles, >> >> We use rt_intr_create in our code. So I am trying to understand the >> reasons for it being deprecated. So far, I have not been able to see >> any comments in the code regarding the deprecation or anything in the git > log. > > Splitting your code between driver and application enforces a clean > separation between the two, which helps maintenance, so is good on the long > run. > >> >> Can you pl comment on the reasons for deprecating rt_intr_create? Will >> it be removed in the next release? > > We never change ABI in a branch, so, all releases in the 2.6 branch are > guaranteed to support the same services as xenomai 2.6.0. > > But in xenomai 3.0, rt_intr_create will certainly no longer be available. -- Philippe. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 18:13 ` Philippe Gerum @ 2011-12-23 23:06 ` Terry Fryar 2012-01-19 19:41 ` Michael Pustylnik 1 sibling, 0 replies; 11+ messages in thread From: Terry Fryar @ 2011-12-23 23:06 UTC (permalink / raw) To: 'Philippe Gerum', xenomai Yeh, this is the direction we were going anyways, as I really only need the irq to trigger an unblock in userland. I've already got a kernel driver written using xenomai, so moving the irq code into a driver won't be a stretch!! -----Original Message----- From: Philippe Gerum [mailto:rpm@xenomai.org] Sent: Friday, December 23, 2011 12:13 PM To: xenomai@xenomai.org Cc: terry.fryar@domain.hid Subject: Re: [Xenomai-help] Interrupt numbers On 12/23/2011 05:16 PM, Terry Fryar wrote: > I would imagine it was nice, however, to have a userspace interrupt > ISR so that flaky code could be debugged in userspace before making it > into a driver? > Most interrupts are level sensitive these days, which means that you cannot safely step into the code which is supposed to ack the source device using a debugger, your kernel would be stormed by IRQs before you reach the point where the device request is acked. Remember that userland always runs with hw interrupts enabled, regardless of the domain. Even edge triggered IRQs would not give you any guarantee with respect to device timing requirements. GDB aside, also think about a transition to secondary mode for whatever reason while running in userland prior to acking the device: this would be another source of unexpected delays in the acknowledge path. Debugging work is likely to introduce these issues, unless one refrains from using anything else than rt_printf() for logging/observing the runtime state, but that would not help with level sensitive IRQs anyway. You may want to handle the main application logic that responds to an interrupt in userland through, in which case you need some RTDM driver handling the bottom half of real-time interrupts, which would in turn unblock a task sleeping on some read() or ioctl(), to process the event in userland (i.e. UIO-like for real-time IRQs). The bottom line is that you want the IRQ to be acknowledged at device level from kernel space. Keeping it masked in the PIC while transitioning to user-space would be another option, assuming it is not shared with the regular kernel (sharing between rt and non-rt would be just wrong anyway), if the device permits (infinitely) delayed acknowledges, but I would not recommend this. Typically, a user-space code can be wiped off at any time, leaving the device in a weird state. These are the reasons why I have killed the rt_intr_* API in 3.x, it was way too easy to shoot oneself in the foot (and believe me, I saw quite a few damaged feet in the past years due to this issue). What was missing in this API is a clear hint that some user-provided code should live in kernel space to ack each particular device controlled from userland. Using RTDM to implement such code and synchronize with the application logic in userland is a safe, sane and simple solution. > -----Original Message----- > From: xenomai-help-bounces@domain.hid > [mailto:xenomai-help-bounces@domain.hid] On Behalf Of Gilles > Chanteperdrix > Sent: Friday, December 23, 2011 9:53 AM > To: Makarand Pradhan > Cc: xenomai@xenomai.org > Subject: Re: [Xenomai-help] Interrupt numbers > > On 12/23/2011 04:26 PM, Makarand Pradhan wrote: >> On 23/12/11 04:45 AM, Gilles Chanteperdrix wrote: >>> >>> Xenomai uses the same interrupt numbers as linux. But rt_intr_create >>> is deprecated in user-space, you should instead write a driver using >>> the rtdm skin. The enable bit is handled by xenomai when you request >>> the irq at xenomai level. >>> >> Hi Gilles, >> >> We use rt_intr_create in our code. So I am trying to understand the >> reasons for it being deprecated. So far, I have not been able to see >> any comments in the code regarding the deprecation or anything in the >> git > log. > > Splitting your code between driver and application enforces a clean > separation between the two, which helps maintenance, so is good on the > long run. > >> >> Can you pl comment on the reasons for deprecating rt_intr_create? >> Will it be removed in the next release? > > We never change ABI in a branch, so, all releases in the 2.6 branch > are guaranteed to support the same services as xenomai 2.6.0. > > But in xenomai 3.0, rt_intr_create will certainly no longer be available. -- Philippe. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 18:13 ` Philippe Gerum 2011-12-23 23:06 ` Terry Fryar @ 2012-01-19 19:41 ` Michael Pustylnik 2012-01-19 22:59 ` Philippe Gerum 1 sibling, 1 reply; 11+ messages in thread From: Michael Pustylnik @ 2012-01-19 19:41 UTC (permalink / raw) To: Philippe Gerum, xenomai@xenomai.org; +Cc: Makarand Pradhan Hi Philippe, I am really sorry for continuing this thread after such a long delay but I just couldn't get to it sooner. I understand all your points you mentioned describing the rationale behind your decision to eliminate the rt_intr_* API in Xenomai 3.x, and I definitely agree that they are very valid. However, in real life different Xenomai users could have all kinds of different considerations (other than the ones you mentioned) and there might be special reasons for insisting on using the user space interrupt services. We happen to be one of such users and we have strong reasons to tolerate the potential issues you mentioned in order to achieve our very specific goals by using the rt_intr_* API. (I don't want to waste your time describing those specific goals but believe me there are ones). Said that, we would face serious problems with upgrading to Xenomai 3.x, while we actually do want to take advantage of it. So, my question is simple - could you guys consider leaving the existing rt_intr* services in place as a bonus? (You could still say that this is not a recommended way interrupt handling but it's there for backwards compatibility). Thanks, Michael. -----Original Message----- From: xenomai-help-bounces@domain.hid [mailto:xenomai-help-bounces@domain.hid] On Behalf Of Philippe Gerum Sent: Friday, December 23, 2011 1:13 PM To: xenomai@xenomai.org Subject: Re: [Xenomai-help] Interrupt numbers On 12/23/2011 05:16 PM, Terry Fryar wrote: > I would imagine it was nice, however, to have a userspace interrupt ISR so > that flaky code could be debugged in userspace before making it into a > driver? > Most interrupts are level sensitive these days, which means that you cannot safely step into the code which is supposed to ack the source device using a debugger, your kernel would be stormed by IRQs before you reach the point where the device request is acked. Remember that userland always runs with hw interrupts enabled, regardless of the domain. Even edge triggered IRQs would not give you any guarantee with respect to device timing requirements. GDB aside, also think about a transition to secondary mode for whatever reason while running in userland prior to acking the device: this would be another source of unexpected delays in the acknowledge path. Debugging work is likely to introduce these issues, unless one refrains from using anything else than rt_printf() for logging/observing the runtime state, but that would not help with level sensitive IRQs anyway. You may want to handle the main application logic that responds to an interrupt in userland through, in which case you need some RTDM driver handling the bottom half of real-time interrupts, which would in turn unblock a task sleeping on some read() or ioctl(), to process the event in userland (i.e. UIO-like for real-time IRQs). The bottom line is that you want the IRQ to be acknowledged at device level from kernel space. Keeping it masked in the PIC while transitioning to user-space would be another option, assuming it is not shared with the regular kernel (sharing between rt and non-rt would be just wrong anyway), if the device permits (infinitely) delayed acknowledges, but I would not recommend this. Typically, a user-space code can be wiped off at any time, leaving the device in a weird state. These are the reasons why I have killed the rt_intr_* API in 3.x, it was way too easy to shoot oneself in the foot (and believe me, I saw quite a few damaged feet in the past years due to this issue). What was missing in this API is a clear hint that some user-provided code should live in kernel space to ack each particular device controlled from userland. Using RTDM to implement such code and synchronize with the application logic in userland is a safe, sane and simple solution. > -----Original Message----- > From: xenomai-help-bounces@domain.hid [mailto:xenomai-help-bounces@domain.hid] On > Behalf Of Gilles Chanteperdrix > Sent: Friday, December 23, 2011 9:53 AM > To: Makarand Pradhan > Cc: xenomai@xenomai.org > Subject: Re: [Xenomai-help] Interrupt numbers > > On 12/23/2011 04:26 PM, Makarand Pradhan wrote: >> On 23/12/11 04:45 AM, Gilles Chanteperdrix wrote: >>> >>> Xenomai uses the same interrupt numbers as linux. But rt_intr_create >>> is deprecated in user-space, you should instead write a driver using >>> the rtdm skin. The enable bit is handled by xenomai when you request >>> the irq at xenomai level. >>> >> Hi Gilles, >> >> We use rt_intr_create in our code. So I am trying to understand the >> reasons for it being deprecated. So far, I have not been able to see >> any comments in the code regarding the deprecation or anything in the git > log. > > Splitting your code between driver and application enforces a clean > separation between the two, which helps maintenance, so is good on the long > run. > >> >> Can you pl comment on the reasons for deprecating rt_intr_create? Will >> it be removed in the next release? > > We never change ABI in a branch, so, all releases in the 2.6 branch are > guaranteed to support the same services as xenomai 2.6.0. > > But in xenomai 3.0, rt_intr_create will certainly no longer be available. -- Philippe. _______________________________________________ Xenomai-help mailing list Xenomai-help@domain.hid https://mail.gna.org/listinfo/xenomai-help No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.454 / Virus Database: 271.1.1/3990 - Release Date: 12/22/11 19:34:00 ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2012-01-19 19:41 ` Michael Pustylnik @ 2012-01-19 22:59 ` Philippe Gerum 0 siblings, 0 replies; 11+ messages in thread From: Philippe Gerum @ 2012-01-19 22:59 UTC (permalink / raw) To: Michael Pustylnik; +Cc: xenomai@xenomai.org, Makarand Pradhan On 01/19/2012 08:41 PM, Michael Pustylnik wrote: > Hi Philippe, > > I am really sorry for continuing this thread after such a long delay but I just couldn't get to it sooner. > > I understand all your points you mentioned describing the rationale behind your decision to eliminate the rt_intr_* API in Xenomai 3.x, and I definitely agree that they are very valid. However, in real life different Xenomai users could have all kinds of different considerations (other than the ones you mentioned) and there might be special reasons for insisting on using the user space interrupt services. > > We happen to be one of such users and we have strong reasons to tolerate the potential issues you mentioned in order to achieve our very specific goals by using the rt_intr_* API. (I don't want to waste your time describing those specific goals but believe me there are ones). > Said that, we would face serious problems with upgrading to Xenomai 3.x, while we actually do want to take advantage of it. > > So, my question is simple - could you guys consider leaving the existing rt_intr* services in place as a bonus? (You could still say that this is not a recommended way interrupt handling but it's there for backwards compatibility). > Please don't misunderstand this decision, it is 100% based on real life issues involving multiple customer projects, and was not taken lightly. The rationale behind it is that most newcomers should be allowed to expect all interfaces from the native/alchemy API to implement the recommended way of doing things. rt_intr* is completely at odds with this implicit rule: it is error-prone, limited to very specific use cases, and can lead to blatantly wrong app designs and roadblocks. The plan is to provide for a basic uio-like mechanism based on a RTDM driver for dealing with IRQs in userland. Users who insist on dealing with interrupts in userland could use the RTDM/ioctl() interface directly to that driver or wrap the deprecated rt_intr_* calls locally over it. Using a RTDM driver dedicated to such a peculiar task (and it shall be documented that way) could not be a naive decision. > Thanks, > > Michael. > > > > -----Original Message----- > From: xenomai-help-bounces@domain.hid [mailto:xenomai-help-bounces@domain.hid] On Behalf Of Philippe Gerum > Sent: Friday, December 23, 2011 1:13 PM > To: xenomai@xenomai.org > Subject: Re: [Xenomai-help] Interrupt numbers > > On 12/23/2011 05:16 PM, Terry Fryar wrote: >> I would imagine it was nice, however, to have a userspace interrupt ISR so >> that flaky code could be debugged in userspace before making it into a >> driver? >> > > Most interrupts are level sensitive these days, which means that you > cannot safely step into the code which is supposed to ack the source > device using a debugger, your kernel would be stormed by IRQs before you > reach the point where the device request is acked. Remember that > userland always runs with hw interrupts enabled, regardless of the > domain. Even edge triggered IRQs would not give you any guarantee with > respect to device timing requirements. > > GDB aside, also think about a transition to secondary mode for whatever > reason while running in userland prior to acking the device: this would > be another source of unexpected delays in the acknowledge path. > > Debugging work is likely to introduce these issues, unless one refrains > from using anything else than rt_printf() for logging/observing the > runtime state, but that would not help with level sensitive IRQs anyway. > > You may want to handle the main application logic that responds to an > interrupt in userland through, in which case you need some RTDM driver > handling the bottom half of real-time interrupts, which would in turn > unblock a task sleeping on some read() or ioctl(), to process the event > in userland (i.e. UIO-like for real-time IRQs). > > The bottom line is that you want the IRQ to be acknowledged at device > level from kernel space. Keeping it masked in the PIC while > transitioning to user-space would be another option, assuming it is not > shared with the regular kernel (sharing between rt and non-rt would be > just wrong anyway), if the device permits (infinitely) delayed > acknowledges, but I would not recommend this. Typically, a user-space > code can be wiped off at any time, leaving the device in a weird state. > > These are the reasons why I have killed the rt_intr_* API in 3.x, it was > way too easy to shoot oneself in the foot (and believe me, I saw quite a > few damaged feet in the past years due to this issue). What was missing > in this API is a clear hint that some user-provided code should live in > kernel space to ack each particular device controlled from userland. > Using RTDM to implement such code and synchronize with the application > logic in userland is a safe, sane and simple solution. > >> -----Original Message----- >> From: xenomai-help-bounces@domain.hid [mailto:xenomai-help-bounces@domain.hid] On >> Behalf Of Gilles Chanteperdrix >> Sent: Friday, December 23, 2011 9:53 AM >> To: Makarand Pradhan >> Cc: xenomai@xenomai.org >> Subject: Re: [Xenomai-help] Interrupt numbers >> >> On 12/23/2011 04:26 PM, Makarand Pradhan wrote: >>> On 23/12/11 04:45 AM, Gilles Chanteperdrix wrote: >>>> >>>> Xenomai uses the same interrupt numbers as linux. But rt_intr_create >>>> is deprecated in user-space, you should instead write a driver using >>>> the rtdm skin. The enable bit is handled by xenomai when you request >>>> the irq at xenomai level. >>>> >>> Hi Gilles, >>> >>> We use rt_intr_create in our code. So I am trying to understand the >>> reasons for it being deprecated. So far, I have not been able to see >>> any comments in the code regarding the deprecation or anything in the git >> log. >> >> Splitting your code between driver and application enforces a clean >> separation between the two, which helps maintenance, so is good on the long >> run. >> >>> >>> Can you pl comment on the reasons for deprecating rt_intr_create? Will >>> it be removed in the next release? >> >> We never change ABI in a branch, so, all releases in the 2.6 branch are >> guaranteed to support the same services as xenomai 2.6.0. >> >> But in xenomai 3.0, rt_intr_create will certainly no longer be available. > > -- Philippe. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Xenomai-help] Interrupt numbers 2011-12-23 15:53 ` Gilles Chanteperdrix 2011-12-23 16:16 ` Terry Fryar @ 2011-12-23 16:17 ` Makarand Pradhan 1 sibling, 0 replies; 11+ messages in thread From: Makarand Pradhan @ 2011-12-23 16:17 UTC (permalink / raw) To: Gilles Chanteperdrix; +Cc: xenomai@xenomai.org Thanks. On 23/12/11 10:53 AM, Gilles Chanteperdrix wrote: > On 12/23/2011 04:26 PM, Makarand Pradhan wrote: >> On 23/12/11 04:45 AM, Gilles Chanteperdrix wrote: >>> Xenomai uses the same interrupt numbers as linux. But rt_intr_create is >>> deprecated in user-space, you should instead write a driver using the >>> rtdm skin. The enable bit is handled by xenomai when you request the irq >>> at xenomai level. >>> >> Hi Gilles, >> >> We use rt_intr_create in our code. So I am trying to understand the >> reasons for it being deprecated. So far, I have not been able to see any >> comments in the code regarding the deprecation or anything in the git log. > Splitting your code between driver and application enforces a clean > separation between the two, which helps maintenance, so is good on the > long run. > >> Can you pl comment on the reasons for deprecating rt_intr_create? Will >> it be removed in the next release? > We never change ABI in a branch, so, all releases in the 2.6 branch are > guaranteed to support the same services as xenomai 2.6.0. > > But in xenomai 3.0, rt_intr_create will certainly no longer be available. -- ___________________________________________________________________________ NOTICE OF CONFIDENTIALITY: This e-mail and any attachments may contain confidential and privileged information. If you are not the intended recipient, please notify the sender immediately by return e-mail and delete this e-mail and any copies. Any dissemination or use of this information by a person other than the intended recipient is unauthorized and may be illegal. _____________________________________________________________________ ^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2012-01-19 22:59 UTC | newest] Thread overview: 11+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2011-12-23 0:38 [Xenomai-help] Interrupt numbers Terry Fryar 2011-12-23 9:45 ` Gilles Chanteperdrix 2011-12-23 14:04 ` Terry Fryar 2011-12-23 15:26 ` Makarand Pradhan 2011-12-23 15:53 ` Gilles Chanteperdrix 2011-12-23 16:16 ` Terry Fryar 2011-12-23 18:13 ` Philippe Gerum 2011-12-23 23:06 ` Terry Fryar 2012-01-19 19:41 ` Michael Pustylnik 2012-01-19 22:59 ` Philippe Gerum 2011-12-23 16:17 ` Makarand Pradhan
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