mirror of
https://github.com/tailix/libkernaux.git
synced 2024-10-30 11:54:01 -04:00
71 lines
2.8 KiB
C
71 lines
2.8 KiB
C
#include <kernaux/pfa.h>
|
|
|
|
#include <assert.h>
|
|
|
|
// Create PFA in some static memory area because typically you don't have memory
|
|
// management in kernel without PFA.
|
|
struct KernAux_PFA pfa;
|
|
|
|
void example_main()
|
|
{
|
|
// In the earliest stage of kernel initialization mark all pages as
|
|
// unavailable because you don't have memory map yet.
|
|
KernAux_PFA_initialize(&pfa);
|
|
|
|
// Let's assume that you have the following memory map now:
|
|
// * [0 B; 64 KiB)
|
|
// * [1 MiB; 4 MiB)
|
|
// * [6 MiB; 128 MiB)
|
|
// Mark these pages as available. Note that page is identified by any
|
|
// address inside it. This is why you can subtract 1, not only
|
|
// KERNAUX_PFA_PAGE_SIZE.
|
|
KernAux_PFA_mark_available(&pfa, 0, 1024 * 64 - 1);
|
|
KernAux_PFA_mark_available(&pfa, 1024 * 1024, 1024 * 1024 * 4 - 1);
|
|
KernAux_PFA_mark_available(&pfa, 1024 * 1024 * 6, 1024 * 1024 * 128 - 1);
|
|
|
|
// You can test page availability.
|
|
assert(KernAux_PFA_is_available(&pfa, 1024 * 32)); // 32 KiB
|
|
assert(!KernAux_PFA_is_available(&pfa, 1024 * 64)); // 64 KiB
|
|
assert(KernAux_PFA_is_available(&pfa, 1024 * 1024)); // 1 MiB
|
|
assert(!KernAux_PFA_is_available(&pfa, 1024 * 1024 * 6 // 6 MiB - 4 KiB
|
|
- KERNAUX_PFA_PAGE_SIZE));
|
|
assert(KernAux_PFA_is_available(&pfa, 1024 * 1024 * 128 // 128 MiB - 4 KiB
|
|
- KERNAUX_PFA_PAGE_SIZE));
|
|
assert(!KernAux_PFA_is_available(&pfa, 1024 * 1024 * 128)); // 128 MiB
|
|
|
|
// When you have configured PFA, you can use it to allocate and free pages.
|
|
{
|
|
const size_t page_addr =
|
|
KernAux_PFA_alloc_pages(&pfa, KERNAUX_PFA_PAGE_SIZE);
|
|
assert(!KernAux_PFA_is_available(&pfa, page_addr));
|
|
KernAux_PFA_free_pages(&pfa, page_addr, KERNAUX_PFA_PAGE_SIZE);
|
|
assert(KernAux_PFA_is_available(&pfa, page_addr));
|
|
}
|
|
|
|
// You can also allocate multiple continuous pages.
|
|
{
|
|
const size_t page_addr =
|
|
KernAux_PFA_alloc_pages(&pfa, 10 * KERNAUX_PFA_PAGE_SIZE);
|
|
|
|
for (size_t index = 0, addr = page_addr; index < 10; ++index) {
|
|
assert(!KernAux_PFA_is_available(&pfa, addr));
|
|
addr += KERNAUX_PFA_PAGE_SIZE;
|
|
}
|
|
|
|
KernAux_PFA_free_pages(&pfa, page_addr, 10 * KERNAUX_PFA_PAGE_SIZE);
|
|
|
|
for (size_t index = 0, addr = page_addr; index < 10; ++index) {
|
|
assert(KernAux_PFA_is_available(&pfa, addr));
|
|
addr += KERNAUX_PFA_PAGE_SIZE;
|
|
}
|
|
}
|
|
|
|
// You can also request amounts of memory which are not factors of page
|
|
// size.
|
|
{
|
|
const size_t page_addr = KernAux_PFA_alloc_pages(&pfa, 123);
|
|
assert(!KernAux_PFA_is_available(&pfa, page_addr));
|
|
KernAux_PFA_free_pages(&pfa, page_addr, 123);
|
|
assert(KernAux_PFA_is_available(&pfa, page_addr));
|
|
}
|
|
}
|