# US 7,080,179 B1 · Multi-level interrupts > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,080,179 B1 - Document ID: US7080179B1 - Status: Granted - Kind: B1 - Application number: 10/810,057 - Filed: 2004-03-26 - Granted: 2006-07-18 - Earliest claimed: 2004-03-26 - Assignees: Foundry Networks, Inc. - Inventors: Changbai He; Ron Talmor - Web page: https://patentgrep.com/patent/US7080179B1 ## CPC - G06F 13/24: using interrupt (G06F13/32 takes precedence) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract Multiple levels of interrupts to be utilized in a computer system, which allows, for example, an interrupt with an interrupt level associated with an application to be distinct from an interrupt with an interrupt level associated with a kernel. The kernel level interrupt may be handled quickly via its own handler, while the application level interrupt may be handled more slowly. This may be accomplished by first determining if a first-level handler is installed for the interrupt source. If so, then it may be called. Otherwise, the interrupt source may be masked and a second-level handler may be called. Once this second-level handler has completed its tasks, the interrupt source may then be unmasked. Implementations with three or more levels of interrupt are also possible. ## Claims ### Claim 1 A method for handling an interrupt in a computer system, the interrupt having a source, the method comprising: determining if a first-level handler is installed for the interrupt source; calling said first-level handler if one is installed for the interrupt source; masking the interrupt source if a first-level handler is not installed for the interrupt source; calling a second-level handler if a first-level handler is not installed for the interrupt source; and unmasking the interrupt source if a first-level handler is not installed for the interrupt source. ### Claim 2 (depends on 1) The method of claim 1, further comprising: retrieving the interrupt source. ### Claim 3 (depends on 1) The method of claim 1, further comprising: determining if the interrupt source is active; and returning from the method if the interrupt source is not active. ### Claim 4 (depends on 1) The method of claim 1, further comprising: setting an interrupt pending flag for the interrupt source before said calling a second-level handler if a first level-handler is not installed for the interrupt source. ### Claim 5 (depends on 4) The method of claim 4, wherein said calling a second-level handler includes: clearing the pending interrupt flag for the interrupt source. ### Claim 6 (depends on 1) The method of claim 1, wherein said first-level handler is a kernel-level handler. ### Claim 7 (depends on 1) The method of claim 1, wherein said second-level handler is a user-level handler. ### Claim 8 A method for handling an interrupt in a computer system, the interrupt having a source, the method comprising: determining if a first-level handler is installed for the interrupt source; calling said first-level handler if one is installed for the interrupt source; masking the interrupt source if a first-level handler is not installed for the interrupt source; determining if a second-level handler is installed for the interrupt source if a first-level handler is not installed for the interrupt source; calling said second-level handler if a first-level handler is not installed for the interrupt source and a second-level handler is installed for the interrupt source; and unmasking the interrupt source if a first-level handler is not installed for the interrupt source. ### Claim 9 (depends on 8) The method of claim 8, further comprising: determining if a third-level handler is installed for the interrupt source if a first-level handler is not installed for the interrupt source and a second-level handler is not installed for the interrupt source; and calling said third-level handler if a first-level handler is not installed for the interrupt source, a second-level handler is not installed for the interrupt source, and a third-level handler is installed for the interrupt source. ### Claim 10 (depends on 8) The method of claim 8, further comprising: retrieving the interrupt source. ### Claim 11 (depends on 8) The method of claim 8, further comprising: determining if the interrupt source is active; and returning from the method if the interrupt source is not active. ### Claim 12 (depends on 8) The method of claim 8, further comprising: setting an interrupt pending flag for the interrupt source before said calling said second-level handler. ### Claim 13 (depends on 12) The method of claim 12, wherein said calling a second-level handler includes: clearing the pending interrupt flag for the interrupt source. ### Claim 14 An apparatus for handling an interrupt in a computer system, the interrupt having a source, the apparatus comprising: an installed first-level handler determiner; a first-level handler caller coupled to said installed first-level handler determiner; an interrupt source masker coupled to said installed-first level handler determiner; an installed second-level handler determiner coupled to said interrupt source masker; a second-level handler caller coupled to said installed second-level handler determiner; and an interrupt source unmasker coupled to said second-level handler caller. ### Claim 15 (depends on 14) The apparatus of claim 14, further comprising: an installed third-level handler determiner coupled to said installed second-level handler determiner; and a third-level handler caller coupled to said installed third-level handler determiner and to said interrupt source unmasker. ### Claim 16 (depends on 14) The apparatus of claim 14, further comprising: an interrupt source retriever coupled to said installed first-level handler determiner. ### Claim 17 (depends on 14) The apparatus of claim 14, further comprising: an interrupt source active determiner coupled to said installed first-level handler determiner; and a method returner coupled to said interrupt source active determiner. ### Claim 18 (depends on 14) The apparatus of claim 14, further comprising: an interrupt pending flag setter coupled to said interrupt source masker. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein said second-level handler caller includes a pending interrupt flag clearer. ### Claim 20 An apparatus for handling an interrupt in a computer system, the interrupt having a source, the apparatus comprising: means for determining if a first-level handler is installed for the interrupt source; means for calling said first-level handler if one is installed for the interrupt source; means for masking the interrupt source if a first-level handler is not installed for the interrupt source; means for calling a second-level handler if a first-level handler is not installed for the interrupt source; and means for unmasking the interrupt source if a first-level handler is not installed for the interrupt source. ### Claim 21 (depends on 20) The apparatus of claim 20, further comprising: means for retrieving the interrupt source. ### Claim 22 (depends on 20) The apparatus of claim 20, further comprising: means for determining if the interrupt source is active; and means for returning from the method if the interrupt source is not active. ### Claim 23 (depends on 20) The apparatus of claim 20, further comprising: means for setting an interrupt pending flag for the interrupt source before said calling a second-level handler if a first level-handler is not installed for the interrupt source. ### Claim 24 (depends on 23) The apparatus of claim 23, wherein said means for calling a second-level handler includes: means for clearing the pending interrupt flag for the interrupt source. ### Claim 25 (depends on 20) The apparatus of claim 20, wherein said first-level handler is a kernel-level handler. ### Claim 26 (depends on 20) The apparatus of claim 20, wherein said second-level handler is a user-level handler. ### Claim 27 An apparatus for handling an interrupt in a computer system, the interrupt having a source, the apparatus comprising: means for determining if a first-level handler is installed for the interrupt source; means for calling said first-level handler if one is installed for the interrupt source; means for masking the interrupt source if a first-level handler is not installed for the interrupt source; means for determining if a second-level handler is installed for the interrupt source if a first-level handler is not installed for the interrupt source; means for calling said second-level handler if a first-level handler is not installed for the interrupt source and a second-level handler is installed for the interrupt source; and means for unmasking the interrupt source if a first-level handler is not installed for the interrupt source. ### Claim 28 (depends on 27) The apparatus of claim 27, further comprising: means for determining if a third-level handler is installed for the interrupt source if a first-level handler is not installed for the interrupt source and a second-level handler is not installed for the interrupt source; and means for calling said third-level handler if a first-level handler is not installed for the interrupt source, a second-level handler is not installed for the interrupt source, and a third-level handler is installed for the interrupt source. ### Claim 29 (depends on 27) The apparatus of claim 27, further comprising: means for retrieving the interrupt source. ### Claim 30 (depends on 27) The apparatus of claim 27, further comprising: means for determining if the interrupt source is active; and means for returning from the method if the interrupt source is not active. ### Claim 31 (depends on 27) The apparatus of claim 27, further comprising: means for setting an interrupt pending flag for the interrupt source before said calling said second-level handler. ### Claim 32 (depends on 31) The apparatus of claim 31, wherein said means for calling a second-level handler includes: means for clearing the pending interrupt flag for the interrupt source. ### Claim 33 A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform a method for handling an interrupt in a computer system, the interrupt having a source, the method comprising: determining if a first-level handler is installed for the interrupt source; calling said first-level handler if one is installed for the interrupt source; masking the interrupt source if a first-level handler is not installed for the interrupt source; calling a second-level handler if a first-level handler is not installed for the interrupt source; and unmasking the interrupt source if a first-level handler is not installed for the interrupt source. ### Claim 34 A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform a method for handling an interrupt in a computer system, the interrupt having a source, the method comprising: determining if a first-level handler is installed for the interrupt source; calling said first-level handler if one is installed for the interrupt source; masking the interrupt source if a first-level handler is not installed for the interrupt source; determining if a second-level handler is installed for the interrupt source if a first-level handler is not installed for the interrupt source; calling said second-level handler if a first-level handler is not installed for the interrupt source and a second-level handler is installed for the interrupt source; and unmasking the interrupt source if a first-level handler is not installed for the interrupt source.