Permanent allocation of a large host memory

1. A computer-implemented method for allocating memory from a host computer for an add-in card, the method comprising performing, by the host computer, computer-implemented operations for:

intercepting a first interrupt for resetting a mass storage device;

in response to intercepting the first interrupt for resetting the mass storage device, reading a system address map, modifying the system address map by adding an entry for an amount of host memory to be allocated to the add-in card, storing the modified system address map as a destination system address map, changing an address of a second interrupt handler for handling interrupts for reporting the system address map, and storing an address of an original interrupt handler for handling interrupts for reporting the system address map in a memory of the add-in card;

intercepting a second interrupt for reporting the system address map;

determining whether the second interrupt is memory related;

in response to determining that the second interrupt is memory related, providing the destination system address map; and

in response to determining that the second interrupt is not memory related, calling the original interrupt handler at the stored address.

2. The computer-implemented method of claim 1 , wherein the first interrupt for resetting a mass storage device comprises an interrupt 13h, AH=00h, in an x86-based computing system.

3. The computer-implemented method of claim 1 , wherein the second interrupt comprises an interrupt 15h in an x86-based computing system.

4. The computer-implemented method of claim 1 , further comprising in response to intercepting the first interrupt for resetting the mass storage device:

determining whether a flag indicating that the system address map has been modified has been previously set; and

in response to determining that the flag has been previously set, resetting the mass storage device without performing the operations of modifying the system address map, storing a modified system address map, and changing an address of an interrupt handler for providing the system address map.

5. The computer-implemented method of claim 1 , wherein the destination system address map is stored in the memory of the add-in card.

6. The computer-implemented method of claim 1 , wherein the first interrupt for resetting a mass storage device is intercepted by program code stored in an add-in card option read-only memory (ROM).

7. The computer-implemented method of claim 1 , wherein the second interrupt is intercepted by program code stored in an add-in card option read-only memory (ROM).

8. The computer-implemented method of claim 1 , wherein changing the address of the second interrupt handler for handling interrupts for reporting the system address map comprises modifying an interrupt vector table for the second interrupt handler to point to an address of another interrupt handler.

9. The computer-implemented method of claim 1 , wherein the add-in card comprises a mass storage device controller card.

10. A computer-readable storage medium having computer-executable instructions stored thereupon which, when executed by a computer, cause the computer to:

intercept an interrupt for resetting a mass storage device;

in response to intercepting the interrupt for resetting the mass storage device, read a system address map, modify the system address map by adding an entry for an amount of host memory to be allocated to an add-in card, store the modified system address map as a destination system address map, change an address of an interrupt handler for handling interrupts for reporting the system address map, and store an address of an original interrupt handler for handling interrupts for reporting the system address map in a memory of the add-in card;

intercept an interrupt for reporting the system address map; and

provide the destination system address map in response to intercepting the interrupt for reporting the system address map.

11. The computer-readable storage medium of claim 10 , wherein the interrupt for resetting a mass storage device comprises an interrupt 13h, AH=00h, in an x86-based computing system and wherein the interrupt for reporting the system address map comprises an interrupt 15h, AX=E820, in an x86-based computing system.

12. The computer-readable storage medium of claim 11 , having further computer-readable instructions stored thereupon which, when executed by the computer, cause the computer to:

determine whether a flag indicating that the system address map has been modified has been previously set; and

in response to determining that the flag has been previously set, reset the mass storage device without performing the operations to modify the system address map, store a modified system address map, and change an address of an interrupt handler for providing the system address map.

13. The computer-readable storage medium of claim 12 , wherein the destination system address map is stored in the memory of the add-in card.

14. The computer-readable storage medium of claim 10 , having further computer-readable instructions stored thereupon which, when executed by the computer, cause the computer to:

determine whether the interrupt for reporting the system address map is memory related; and

in response to determining that the interrupt for reporting the system address map is not memory related, to call the original interrupt handler for handling interrupts for reporting the system address map at the stored address.

15. The computer-readable storage medium of claim 10 , wherein the interrupt for resetting a mass storage device is intercepted by program code stored in an add-in card option read-only memory (ROM).

16. The computer-implemented method of claim 10 , wherein the interrupt for reporting the system address map is intercepted by program code stored in an add-in card option read-only memory (ROM).

17. A computer system add-in card comprising:

an option read-only memory (ROM) storing computer-readable instructions executable by a host computer comprising

a first interrupt handler for handling an interrupt for resetting a mass storage device, and configured, when called, to read a system address map, to modify the system address map by adding an entry for an amount of host memory to be allocated to the add-in card, to store the modified system address map as a destination system address map, to change an address of an interrupt handler for handling interrupts for reporting the system address map, and to store an address of an original interrupt handler for handling interrupts for reporting the system address map in a memory of the add-in card, and

a second interrupt handler for handling an interrupt for reporting the system address map, and configured to provide the destination system address map when called.

18. The computer-system add-in card of claim 17 , wherein the interrupt for resetting a mass storage device comprises an interrupt 13h, AH=00h, in an x86-based computing system and wherein the interrupt for reporting the system address map comprises an interrupt 15h, AX=E820, in an x86-based computing system.

19. The computer-system add-in card of claim 17 , wherein the first interrupt handler is further configured when called to determine whether a flag indicating that the system address map has been modified has been previously set, and in response to determining that the flag has been previously set, to reset a mass storage device without performing the operations to modify the system address map, store a modified system address map, and change an address of an interrupt handler for providing the system address map.