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

#

#      interrupts.cdl

#

#      configuration data related to kernel interrupt handling

#

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

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

######DESCRIPTIONBEGIN####

#

# Author(s):      bartv

# Original data:  nickg

# Contributors:

# Date:           1999-06-13

#

#####DESCRIPTIONEND####

#

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

# NOTE: the choice of list vs table should not be two separate

# options. There is a single option which must have one of

# two legal values.

cdl_component CYGIMP_KERNEL_INTERRUPTS_DSRS {

    display       "Use delayed service routines (DSRs)"

    default_value 1

    description   "

        In eCos the recommended way to handle device interrupts is to

        do a minimum amount of work inside the low level interrupt

        handler itself, and instead do as much as possible in a

        Delayed Service Routine or DSR. If an application does not

        make use of DSRs directly or indirectly then it is possible

        to disable the DSR support completely, which reduces the

        overheads of context switches and interrupt handling. Note

        that the kernel real-time clock makes use of DSRs, as do many

        of the device drivers. "

    cdl_interface CYGINT_KERNEL_INTERRUPTS_DSRS {

        requires 1 == CYGINT_KERNEL_INTERRUPTS_DSRS

        no_define

    }

    # NOTE: the choice of list vs table should not be two separate

    # options. There is a single option which must have one of

    # two legal values.

    cdl_option CYGIMP_KERNEL_INTERRUPTS_DSRS_LIST {

        display       "Use linked lists for DSRs"

        default_value 1

        implements    CYGINT_KERNEL_INTERRUPTS_DSRS

        description   "

            When DSR support is enabled the kernel must keep track of all

            the DSRs that are pending. This information can be kept in a

            fixed-size table or in a linked list. The list implementation

            requires that the kernel disable interrupts for a very short

            period of time outside interrupt handlers, but there is no

            possibility of a table overflow occurring."

    }

    cdl_component CYGIMP_KERNEL_INTERRUPTS_DSRS_TABLE {

        display       "Use fixed-size table for DSRs"

        default_value 0

        implements    CYGINT_KERNEL_INTERRUPTS_DSRS

        description   "

            When DSR support is enabled the kernel must keep track of all

            the DSRs that are pending. This information can be kept in a

            fixed-size table or in a linked list. The table

            implementation involves a very small risk of overflow at

            run-time if a given interrupt source is able to have more

            than one pending DSR. However it has the advantage that

            the kernel does not need to disable interrupts outside

            interrupt handlers."

        cdl_option CYGNUM_KERNEL_INTERRUPTS_DSRS_TABLE_SIZE {

            display       "Number of entries in fixed-size DSR table"

            flavor        data

            legal_values  2 to 1024

            default_value 32

            description "

            When DSR support is enabled the kernel must keep track of all

            the DSRs that are pending. One approach involves a fixed-size

            table, which involves a very small risk of overflow at

            run-time. By increasing the table size it is possible to reduce

            this risk."

        }

    }

    cdl_option CYGIMP_KERNEL_INTERRUPTS_CHAIN {

        display       "Chain all interrupts together"

        requires      CYGIMP_HAL_COMMON_INTERRUPTS_CHAIN

        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."

    }

}