Allocate a large amount of continuous memory when Linux is started

During Linux boot, a large amount of continuous memory is allocated-Linux general technology-Linux programming and kernel information. The following is a detailed description. I mentioned in LDD that there are several ways to obtain a large number of continuous memories.

1) set parameter Line parameter mem = XXM

2) keep the memory at startup

The first method was used before, but the boot loader should be used together.

In this experiment, the second method is used.

The prototype and header are as follows:

# Include linux/bootmem. h
Void * alloc_bootmem (unsigned long size );
Void * alloc_bootmem_low (unsigned long size );
Void * alloc_bootmem_pages (unsigned long size );
Void * alloc_bootmem_low_pages (unsigned long size );

Steps:

1) Modify init/main. c and find the start_kernel Function

2) After setup_arch (...), add the program code alloc_bootmem_XX

3) output the obtained indicator export.