Efficient reclamation of pre-allocated direct memory access (DMA) memory

1. A method for efficient reclamation of pre-allocated direct memory access (DMA) memory using a processor device in a computing environment, the method comprising:

emulating a hot-add RAM for a general purpose use by reclamation of pre-allocated DMA memory reserved at boot time by notifying a non-kernel use device user that the non-kernel use device has a smaller window, stopping and remapping to the smaller window, and notifying a kernel that new memory has been added, wherein the new memory is a region left after the remap;

stopping the application requiring the non-kernel use device;

stopping operations of the non-kernel use device by a device driver; and

unmapping a buffer from a kernel virtual mapping system.

2. The method of claim 1 , further including splitting the hot-add RAM into at least two continuous parts.

3. The method of claim 2 , further including remapping at least one of the two continuous parts of the hot-add RAM for use by DMA memory of the non-kernel use device, wherein the new memory is at least one of the two continuous parts.

4. The method of claim 3 , further including signaling the kernel of the addition of the hot-add RAM.

5. The method of claim 4 , further including performing at least one of:

scanning the at least one of the two continuous parts of the hot-add RAM by the kernel,

perceiving that the least one of the two continuous parts of the hot-add RAM is newly added, and

adding the least one of the two continuous parts of the hot-add RAM to a pool of general purpose memory.

6. The method of claim 5 , further including configuring the non-kernel use device with the buffer of the least one of the two continuous parts of the hot-add RAM.

7. A system for efficient reclamation of pre-allocated direct memory access (DMA) memory in a computing environment, the system comprising:

at least one processor device operable in the computing environment, wherein the at least one processor device:

emulates a hot-add random access memory (RAM) for a general purpose use by reclamation of pre-allocated DMA memory reserved at boot time by notifying a non-kernel use device user that the non-kernel use device has a smaller window, stopping and remapping to the smaller window, and notifying a kernel that new memory has been added, wherein the new memory is a region left after the remap,

stops the application requiring the non-kernel use device,

stops operations of the non-kernel use device by a device driver, and

unmaps a buffer from a kernel virtual mapping system.

8. The system of claim 7 , wherein the at least one processor device splits the hot-add RAM into at least two continuous parts.

9. The system of claim 8 , wherein the at least one processor device remaps at least one of the two continuous parts of the hot-add RAM for use by DMA memory of the non-kernel use device, wherein the new memory is at least one of the two continuous parts.

10. The system of claim 9 , wherein the at least one processor device signals the kernel of the addition of the hot-add RAM.

11. The system of claim 10 , wherein the at least one processor device performs at least one of:

scanning the at least one of the two continuous parts of the hot-add RAM by the kernel,

perceiving that the least one of the two continuous parts of the hot-add RAM is newly added, and

adding the least one of the two continuous parts of the hot-add RAM to a pool of general purpose memory.

12. The system of claim 11 , wherein the at least one processor device configuring the non-kernel use device with the buffer of the least one of the two continuous parts of the hot-add RAM.

13. A computer program product for efficient reclamation of pre-allocated direct memory access (DMA) memory using a processor device, the computer program product comprising a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

a first executable portion that emulates a hot-add random access memory (RAM) for a general purpose use by reclamation of pre-allocated DMA memory reserved at boot time by notifying a non-kernel use device user that the non-kernel use device has a smaller window, stopping and remapping to the smaller window, and notifying a kernel that new memory has been added, wherein the new memory is a region left after the remap; and

a second executable portion that stops the application requiring the non-kernel use device,

stops operations of the non-kernel use device by a device driver, and

unmaps a buffer from a kernel virtual mapping system.

14. The computer program product of claim 13 , further includes a third executable portion that performs at least one of:

splitting the hot-add RAM into at least two continuous parts, and

remapping at least one of the two continuous parts of the hot-add RAM for use by DMA memory of the non-kernel use device, wherein the new memory is at least one of the two continuous parts.

15. The computer program product of claim 14 , further includes a fourth executable portion that signals the kernel of the addition of the hot-add RAM.

16. The computer program product of claim 15 , further includes a fifth executable portion that performs at least one of:

scanning the at least one of the two continuous parts of the hot-add RAM by the kernel,

perceiving that the least one of the two continuous parts of the hot-add RAM is newly added, and

adding the least one of the two continuous parts of the hot-add RAM to a pool of general purpose memory.

17. The computer program product of claim 16 , further includes a sixth executable portion that configures the non-kernel use device with the buffer of the least one of the two continuous parts of the hot-add RAM.