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Tidy up memory map a bit and write out the general map in MemoryManager.

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There was a bug that given enough supervisor page allocation, we would
eventually start dipping into the kmalloc range.
This commit is contained in:
Andreas Kling 2019-01-16 00:44:09 +01:00
parent bd3e77cc16
commit a8baee4dcd
Notes: sideshowbarker 2024-07-19 16:01:49 +09:00
2 changed files with 17 additions and 13 deletions
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14
Kernel/MemoryManager.cpp
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@ -69,20 +69,24 @@ void MemoryManager::initialize_paging()
// The bottom 4 MB (except for the null page) are identity mapped & supervisor only.
// Every process shares these mappings.
create_identity_mapping(kernel_page_directory(), LinearAddress(PAGE_SIZE), (4 * MB) - PAGE_SIZE);
// Physical pages from this range are used for page tables.
for (size_t i = (1 * MB); i < (4 * MB); i += PAGE_SIZE)
// Basic memory map:
// 0 -> 512 kB Kernel code. Root page directory & PDE 0.
// 1 MB -> 2 MB kmalloc_eternal() space.
// 2 MB -> 3 MB kmalloc() space.
// 3 MB -> 4 MB Supervisor physical pages (available for allocation!)
// 4 MB -> 32 MB Userspace physical pages (available for allocation!)
for (size_t i = (2 * MB); i < (4 * MB); i += PAGE_SIZE)
m_free_supervisor_physical_pages.append(adopt(*new PhysicalPage(PhysicalAddress(i), true)));
#ifdef MM_DEBUG
dbgprintf("MM: 4MB-32MB available for allocation\n");
#endif
// The physical pages 4 MB through 8 MB are available for allocation.
for (size_t i = (4 * MB); i < (32 * MB); i += PAGE_SIZE)
m_free_physical_pages.append(adopt(*new PhysicalPage(PhysicalAddress(i), false)));
m_quickmap_addr = LinearAddress(m_free_physical_pages.takeLast().leakRef()->paddr().get());
kprintf("MM: Quickmap will use P%x\n", m_quickmap_addr.get());
#ifdef MM_DEBUG
dbgprintf("MM: Quickmap will use P%x\n", m_quickmap_addr.get());
dbgprintf("MM: Installing page directory\n");
#endif
asm volatile("movl %%eax, %%cr3"::"a"(kernel_page_directory().cr3()));