Find the answer to your Linux question:
Results 1 to 3 of 3
Hi, is there a List of all Calls save to make from the Top Half of an fast ISR. I would especially like to save the time an interrupt occurs ...
Enjoy an ad free experience by logging in. Not a member yet? Register.
  1. #1
    Just Joined!
    Join Date
    Aug 2009
    Posts
    2

    Top half Fast ISR save call list


    Hi,

    is there a List of all Calls save to make from the Top Half of an fast ISR.

    I would especially like to save the time an interrupt occurs as accurate as possible.

    I only found comments like the available API for an ISR is limited.

    Ingo

  2. #2
    Linux Guru Rubberman's Avatar
    Join Date
    Apr 2009
    Location
    I can be found either 40 miles west of Chicago, or in a galaxy far, far away.
    Posts
    11,175
    Interrupt handlers have to be as fast as possible since at the very least they will block other interrupts on the same IRQ. This is the main reason why the functions allowable in an interrupt handler are limited - no I/O, no blocking calls. Usually they set some flag, increment some variable, and such that the normal kernel module code can process in a more normal manner. In your case, you could read the system clock counter value and store that in some variable in your module memory space that can later be processed for an actual clock time value.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

  3. #3
    Just Joined!
    Join Date
    Aug 2009
    Posts
    2
    H'm

    may be I have to look in the kernelsources myself to get if some func will be good for my ISR or not.
    What do you mean with system clock counter? Jiffies?
    The resolution is not sufficient for me and I also don't know how usuable it is in an tickless system.
    Possibly I also need some fifo/Queue for the data I have to transfer from ISR to bottom.
    I find no entry point for this topics.

    Ingo

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •