Finding the interrupt vector of a given IRQ
In the kernel, how can I find out the interrupt vector number of a given IRQ (for example, IRQ7)? Within the kernel module, I would like to manually set the IRQ using the assembly code: asm("int $<irq vector>"); and let the IRQ handler installed by a different module catch that interrupt. Is this possible? Thanks! Mark
On Sun, May 27, 2012 at 2:02 AM, Mark Farnell <mark.farnell@gmail.com> wrote:
In the kernel, how can I find out the interrupt vector number of a given IRQ (for example, IRQ7)?
Within the kernel module, I would like to manually set the IRQ using the assembly code:
asm("int $<irq vector>");
and let the IRQ handler installed by a different module catch that interrupt.
Is this possible?
No really because not all IRQ have an interrupt line to the CPU. Linux can multiplex and emulate them. Think of GPIO drivers with interrupt support. Anyway, why to you think you need to trigger the raw IRQ manually? This sounds really odd... -- Thanks, //richard
This is for an assignment, where the student needs to write an interrupt handler. Since the OS is run on a virtual machine, I need to find a way to trigger the IRQ to let the students' interrupt handler to handle the interrupt. On Mon, May 28, 2012 at 9:27 AM, richard -rw- weinberger <richard.weinberger@gmail.com> wrote:
On Sun, May 27, 2012 at 2:02 AM, Mark Farnell <mark.farnell@gmail.com> wrote:
In the kernel, how can I find out the interrupt vector number of a given IRQ (for example, IRQ7)?
Within the kernel module, I would like to manually set the IRQ using the assembly code:
asm("int $<irq vector>");
and let the IRQ handler installed by a different module catch that interrupt.
Is this possible?
No really because not all IRQ have an interrupt line to the CPU. Linux can multiplex and emulate them. Think of GPIO drivers with interrupt support. Anyway, why to you think you need to trigger the raw IRQ manually? This sounds really odd...
-- Thanks, //richard
AKAIK I think is possible. For example int 3 in x86 is actually an interrupt so to say. I don't want to go in other details about exception vs interrupts and stack saving. But in short you can achieve what you are trying here. Search for breakpoint handler probably in entry.S and from the trace back to IDT initialization. Replace the vector 3 with your handlers address. Now you can do int 3 from elsewhere in inline assembly. On May 28, 2012 3:40 AM, "Mark Farnell" <mark.farnell@gmail.com> wrote:
This is for an assignment, where the student needs to write an interrupt handler.
Since the OS is run on a virtual machine, I need to find a way to trigger the IRQ to let the students' interrupt handler to handle the interrupt.
On Mon, May 28, 2012 at 9:27 AM, richard -rw- weinberger <richard.weinberger@gmail.com> wrote:
On Sun, May 27, 2012 at 2:02 AM, Mark Farnell <mark.farnell@gmail.com>
wrote:
In the kernel, how can I find out the interrupt vector number of a given IRQ (for example, IRQ7)?
Within the kernel module, I would like to manually set the IRQ using the assembly code:
asm("int $<irq vector>");
and let the IRQ handler installed by a different module catch that interrupt.
Is this possible?
No really because not all IRQ have an interrupt line to the CPU. Linux can multiplex and emulate them. Think of GPIO drivers with interrupt support. Anyway, why to you think you need to trigger the raw IRQ manually? This sounds really odd...
-- Thanks, //richard
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On Mon, May 28, 2012 at 12:09 AM, Mark Farnell <mark.farnell@gmail.com> wrote:
This is for an assignment, where the student needs to write an interrupt handler.
Since the OS is run on a virtual machine, I need to find a way to trigger the IRQ to let the students' interrupt handler to handle the interrupt.
What a stupid assignment! Assignments like this make only sense if you have real hardware... Anyway, create a timer (e.g struct timer_list) which calls your ISR. That's how people test their ISRs. -- Thanks, //richard
Hi.. On Mon, May 28, 2012 at 5:09 AM, Mark Farnell <mark.farnell@gmail.com> wrote:
This is for an assignment, where the student needs to write an interrupt handler.
Since the OS is run on a virtual machine, I need to find a way to trigger the IRQ to let the students' interrupt handler to handle the interrupt.
If you use Qemu, better consult Qemu folks in qemu-devel. Anyway, just for example, timer interrupt in Qemu is actually coming from user space timer trigger (setitimer maybe.... lately it could be coming from HPET too). So, perhaps what you need to do is add another Qemu monitor commands that manually triggers this timer function. Pay attention for the reentrancy issues though. Hope it helps... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
On Mon, May 28, 2012 at 2:57 AM, richard -rw- weinberger <richard.weinberger@gmail.com> wrote:
On Sun, May 27, 2012 at 2:02 AM, Mark Farnell <mark.farnell@gmail.com> wrote:
In the kernel, how can I find out the interrupt vector number of a given IRQ (for example, IRQ7)?
Within the kernel module, I would like to manually set the IRQ using the assembly code:
asm("int $<irq vector>");
and let the IRQ handler installed by a different module catch that interrupt.
Is this possible?
No really because not all IRQ have an interrupt line to the CPU. Linux can multiplex and emulate them. Think of GPIO drivers with interrupt support. Can you please describe this in detail?It would really help a lot of people like me.Does multiplex mean that all numbers starting from 0,1,2,3,...... TOTAL-interrupt will have interrupt lines associated with it eventhough all interrupt numbers are not linear? Anyway, why to you think you need to trigger the raw IRQ manually? This sounds really odd...
-- Thanks, //richard
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Finally got it working....... First, at the kernel source, you need to go to: arch/x86/include/asm/irq_vectors.h to find out which interrupt vector your IRQ is mapped to (replace x86 with your architechure, but for this purpose, amd64 also falls into x86). Then within the kernel space (i.e. in a kernel module function such as ioctl()), make an assembly call: asm("int $<interrupt vector>"); to set the interrupt. In this case, IRQ7 is mapped to 55 for x86/amd64 architecture. Cheers, Mark On Mon, May 28, 2012 at 3:46 PM, anish singh <anish198519851985@gmail.com> wrote:
On Mon, May 28, 2012 at 2:57 AM, richard -rw- weinberger <richard.weinberger@gmail.com> wrote:
On Sun, May 27, 2012 at 2:02 AM, Mark Farnell <mark.farnell@gmail.com> wrote:
In the kernel, how can I find out the interrupt vector number of a given IRQ (for example, IRQ7)?
Within the kernel module, I would like to manually set the IRQ using the assembly code:
asm("int $<irq vector>");
and let the IRQ handler installed by a different module catch that interrupt.
Is this possible?
No really because not all IRQ have an interrupt line to the CPU. Linux can multiplex and emulate them. Think of GPIO drivers with interrupt support. Can you please describe this in detail?It would really help a lot of people like me.Does multiplex mean that all numbers starting from 0,1,2,3,...... TOTAL-interrupt will have interrupt lines associated with it eventhough all interrupt numbers are not linear? Anyway, why to you think you need to trigger the raw IRQ manually? This sounds really odd...
-- Thanks, //richard
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Hi Anish, On Mon, May 28, 2012 at 9:16 AM, anish singh <anish198519851985@gmail.com>wrote:
On Mon, May 28, 2012 at 2:57 AM, richard -rw- weinberger <richard.weinberger@gmail.com> wrote:
On Sun, May 27, 2012 at 2:02 AM, Mark Farnell <mark.farnell@gmail.com> wrote:
In the kernel, how can I find out the interrupt vector number of a given IRQ (for example, IRQ7)?
Within the kernel module, I would like to manually set the IRQ using the assembly code:
asm("int $<irq vector>");
and let the IRQ handler installed by a different module catch that interrupt.
Is this possible?
No really because not all IRQ have an interrupt line to the CPU. Linux can multiplex and emulate them. Think of GPIO drivers with interrupt support. Can you please describe this in detail?It would really help a lot of people like me.Does multiplex mean that all numbers starting from 0,1,2,3,...... TOTAL-interrupt will have interrupt lines associated with it eventhough all interrupt numbers are not linear?
GPIOs are grouped as banks. Let’s say 32 gpios are in a bank. There will be only single interrupt line to interrupt controller for a bank. Consider that you have configured gpio1 and gpio16 as interrupts. Even if interrupt happens on gpio 1 or gpio 16, the same interrupt line will be triggered to Interrupt controller. Now the gpio driver has to figure out reading the Interrupt status Register of GPIO to find which interrupt (gpio1 or gpio16) has really fired. So in this case a single interrupt line is multiplex for 32 gpio interrupts. HTH. Thanks, Arun
Anyway, why to you think you need to trigger the raw IRQ manually? This sounds really odd...
-- Thanks, //richard
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On Fri, 2012-10-19 at 10:34 +0530, Arun KS wrote:
Hi Anish,
On Mon, May 28, 2012 at 9:16 AM, anish singh <anish198519851985@gmail.com> wrote: On Mon, May 28, 2012 at 2:57 AM, richard -rw- weinberger <richard.weinberger@gmail.com> wrote: > On Sun, May 27, 2012 at 2:02 AM, Mark Farnell <mark.farnell@gmail.com> wrote: >> In the kernel, how can I find out the interrupt vector number of a >> given IRQ (for example, IRQ7)? >> >> Within the kernel module, I would like to manually set the IRQ using >> the assembly code: >> >> asm("int $<irq vector>"); >> >> and let the IRQ handler installed by a different module catch that interrupt. >> >> Is this possible? > > No really because not all IRQ have an interrupt line to the CPU. > Linux can multiplex and emulate them. Think of GPIO drivers with > interrupt support.
Can you please describe this in detail?It would really help a lot of people like me.Does multiplex mean that all numbers starting from 0,1,2,3,...... TOTAL-interrupt will have interrupt lines associated with it eventhough all interrupt numbers are not linear?
GPIOs are grouped as banks. Let’s say 32 gpios are in a bank. There will be only single interrupt line to interrupt controller for a bank.
Consider that you have configured gpio1 and gpio16 as interrupts. Even if interrupt happens on gpio 1 or gpio 16, the same interrupt line will be triggered to
Interrupt controller.
Now the gpio driver has to figure out reading the Interrupt status
Register of GPIO to find which interrupt (gpio1 or gpio16) has really fired. And this is done by this way: Suppose we have a chip(mfd-multi-funcion-driver) driver which is connected to processor using a gpio - this gpio line acts as interrupt line from the processor
++++++++++++ ++++++++++ + Processor+ + Chip +---->USB interrupt handler + +gpio--------->+ MFD +---->dock interrupt handler ++++++++++++ + +---->UART interrupt handler ++++++++++---->Factory cable interrupt handler So the code will be as follows: handler_function() { /* find out which interrupt is triggered */ /* it can be usb,dock,uart or factory cable */ ret_irq = read_mfd_register(); /* * ok we found out the interrupt line, get a corresponding * software linux irq number by calling * irq_domain_add_linear * irq_create_mapping * you would have made this calls in the probe probably */ handle_nested_irq(ret_irq); } handle_nested_irq inturn will call all the irq_handlers in the system for your UART,usb and dock driver. mfd_driver() { request_irq(gpio_to_irq(gpio), handler_function); } Hope I have not missed anything.
So in this case a single interrupt line is multiplex for 32 gpio interrupts.
HTH.
Thanks, Arun
> Anyway, why to you think you need to trigger the raw IRQ manually? > This sounds really odd... > > > -- > Thanks, > //richard > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
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Hi Anish, On Sat, Oct 20, 2012 at 9:38 AM, anish kumar <anish198519851985@gmail.com>wrote:
On Fri, 2012-10-19 at 10:34 +0530, Arun KS wrote:
Hi Anish,
On Mon, May 28, 2012 at 9:16 AM, anish singh <anish198519851985@gmail.com> wrote: On Mon, May 28, 2012 at 2:57 AM, richard -rw- weinberger <richard.weinberger@gmail.com> wrote: > On Sun, May 27, 2012 at 2:02 AM, Mark Farnell <mark.farnell@gmail.com> wrote: >> In the kernel, how can I find out the interrupt vector number of a >> given IRQ (for example, IRQ7)? >> >> Within the kernel module, I would like to manually set the IRQ using >> the assembly code: >> >> asm("int $<irq vector>"); >> >> and let the IRQ handler installed by a different module catch that interrupt. >> >> Is this possible? > > No really because not all IRQ have an interrupt line to the CPU. > Linux can multiplex and emulate them. Think of GPIO drivers with > interrupt support.
Can you please describe this in detail?It would really help a lot of people like me.Does multiplex mean that all numbers starting from 0,1,2,3,...... TOTAL-interrupt will have interrupt lines associated with it eventhough all interrupt numbers are not linear?
GPIOs are grouped as banks. Let’s say 32 gpios are in a bank. There will be only single interrupt line to interrupt controller for a bank.
Consider that you have configured gpio1 and gpio16 as interrupts. Even if interrupt happens on gpio 1 or gpio 16, the same interrupt line will be triggered to
Interrupt controller.
Now the gpio driver has to figure out reading the Interrupt status
Register of GPIO to find which interrupt (gpio1 or gpio16) has really fired. And this is done by this way: Suppose we have a chip(mfd-multi-funcion-driver) driver which is connected to processor using a gpio - this gpio line acts as interrupt line from the processor
Interrupt lines are to the interrupt controllor(IC) and only two interrupts lines fom IC(irq and fiq in case of ARM) goes to processor.
++++++++++++ ++++++++++ + Processor+ + Chip +---->USB interrupt handler + +gpio--------->+ MFD +---->dock interrupt handler ++++++++++++ + +---->UART interrupt handler ++++++++++---->Factory cable interrupt handler
So the code will be as follows:
handler_function() { /* find out which interrupt is triggered */ /* it can be usb,dock,uart or factory cable */ ret_irq = read_mfd_register(); /* * ok we found out the interrupt line, get a corresponding * software linux irq number by calling * irq_domain_add_linear * irq_create_mapping * you would have made this calls in the probe probably */ handle_nested_irq(ret_irq); }
handle_nested_irq inturn will call all the irq_handlers in the system for your UART,usb and dock driver.
mfd_driver() { request_irq(gpio_to_irq(gpio), handler_function); }
Yes. This is another example of interrupt multipexing...
Here you have two levels of multiplexing. One for the mfd devices functions and other for gpio. Thanks, Arun
Hope I have not missed anything.
So in this case a single interrupt line is multiplex for 32 gpio interrupts.
HTH.
Thanks, Arun
> Anyway, why to you think you need to trigger the raw IRQ manually? > This sounds really odd... > > > -- > Thanks, > //richard > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
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participants (7)
-
anish kumar -
anish singh
-
Arun KS -
Chauhan, Himanshu -
Mark Farnell -
Mulyadi Santosa -
richard -rw- weinberger