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# ====================================================================

#

#      interrupts.cdl

#

#      HAL interrupt configuration data

#

# ====================================================================

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# ====================================================================

######DESCRIPTIONBEGIN####

#

# Author(s):      jskov

# Original data:  nickg,jskov,jlarmour

# Contributors:

# Date:           1999-07-02

#

#####DESCRIPTIONEND####

#

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cdl_option CYGIMP_HAL_COMMON_INTERRUPTS_USE_INTERRUPT_STACK {

    display       "Use separate stack for interrupts"

    default_value 1

    description   "

        When an interrupt occurs this interrupt can be handled either

        on the current stack or on a separate stack maintained by the

        HAL. Using a separate stack requires a small number of extra

        instructions in the interrupt handling code, but it has the

        advantage that it is no longer necessary to allow extra space

        in every thread stack for the interrupt handlers. The amount

        of extra space required depends on the interrupt handlers

        that are being used."

}

# NOTE: various parts of the system such as device drivers should

# impose lower bounds on this. The actual lower bound depends on a

# platform-specific value for startup overheads, and the minimum

# sizes specified by the various device drivers. If interrupts are

# not handled on a separate stack then only the startup overheads

# are significant. If nested interrupts are disabled then the

# lower bound is the maximum of the individual sizes, otherwise

# it is the sum of these sizes. It is not currently possible to

# express a relationship like this.

cdl_option CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE {

    display       "Interrupt stack size"

    flavor        data

    default_value { CYGPKG_KERNEL ? 4096 : 32768 }

    legal_values  1024 to 1048576

    description   "

        This configuration option specifies the stack size in bytes

        for the interrupt stack. Typically this should be a multiple

        of 16, but the exact requirements will vary from architecture

        to architecture. The interrupt stack serves two separate

        purposes. It is used as the stack during system

        initialization. In addition, if the interrupt system is

        configured to use a separate stack then all interrupts will

        be processed on this stack. The exact memory requirements

        will vary from application to application, and will depend

        heavily on whether or not other interrupt-related options,

        for example nested interrupts, are enabled. On most targets,

        in a configuration with no kernel this stack will also be

        the stack used to invoke the application, and must obviously

        be appropriately large in that case."

}

cdl_option CYGSEM_HAL_COMMON_INTERRUPTS_ALLOW_NESTING {

    display       "Allow nested interrupts"

    default_value 0

    description   "

        When an interrupt occurs the HAL interrupt handling code can

        either leave interrupts disabled for the duration of the

        interrupt handling code, or by doing some extra work it can

        reenable interrupts before invoking the interrupt handler and

        thus allow nested interrupts to happen. If all the interrupt

        handlers being used are small and do not involve any loops

        then it is usually better to disallow nested interrupts.

        However if any of the interrupt handlers are more complicated

        than nested interrupts will usually be required."

}

cdl_option CYGDBG_HAL_COMMON_INTERRUPTS_SAVE_MINIMUM_CONTEXT {

    display       "Save minimum context on interrupt"

    default_value 1

    description   "

        The HAL interrupt handling code can exploit the calling conventions

        defined for a given architecture to reduce the amount of state

        that has to be saved. Generally this improves performance and

        reduces code size. However it can make source-level debugging

        more difficult."

}

cdl_option CYGIMP_HAL_COMMON_INTERRUPTS_CHAIN {

    display       "Chain all interrupts together"

    default_value 0

    description   "

        Interrupts can be attached to vectors either singly, or be

        chained together. The latter is necessary if there is no way

        of discovering which device has interrupted without

        inspecting the device itself. It can also reduce the amount

        of RAM needed for interrupt decoding tables and code."

}

cdl_option CYGIMP_HAL_COMMON_INTERRUPTS_IGNORE_SPURIOUS {

    display       "Ignore spurious \[fleeting\] interrupts"

    default_value 0

    description   "

        On some hardware, interrupt sources may not be de-bounced or

        de-glitched.  Rather than try to handle these interrupts (no

        handling may be possible), this option allows the HAL to simply

        ignore them.  In most cases, if the interrupt is real it will

        reoccur in a detectable form."

}