int l4_kmem_control(unsigned long pfn, int npages, int grant);

• Grant or request free physical pages to/from the microkernel

• A pager may grant some of its free physical memory back to the microkernel.
• pfn argument specifies the physical page frame to grant, npages specifies how many pages the grant spans, grant argument specifies whether this is a memory grant or a request.
• Pagers can dynamically adjust their physical memory quota using this call.

/* A compact memory descriptor to determine used/unused physical pages in the system */
struct page_bitmap {
	unsigned long pfn_start;
	unsigned long pfn_end;
	unsigned int map[PHYSMEM_TOTAL_PAGES >> 5];
};

	/* Pager: Give the kernel some memory to use for its allocators */
	l4_kmem_control(__pfn(alloc_page(__pfn(SZ_1MB))), __pfn(SZ_1MB), 1);

N/A

In the future, this system call will be deprecated and replaced by an L4_CONTAINER_CONTROL system call that implements the same functionality in a generic and elegant way.

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