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Kernel/Memory: Map framebuffer and address space <4GiB

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Address space under 4GiB is used for I/O but is absent
from memory maps on some systems.
This commit is contained in:
Vladimir Serbinenko 2023-07-20 08:36:40 +02:00 committed by Andrew Kaster
parent 342c707be3
commit 160609d80a
Notes: sideshowbarker 2024-07-17 03:16:02 +09:00 
Author: https://github.com/phcoder
Commit: https://github.com/SerenityOS/serenity/commit/160609d80a
Pull-request: https://github.com/SerenityOS/serenity/pull/20150
Reviewed-by: https://github.com/gmta
Reviewed-by: https://github.com/supercomputer7
1 changed files with 13 additions and 0 deletions
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13
Kernel/Memory/MemoryManager.cpp
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@ -417,6 +417,10 @@ UNMAP_AFTER_INIT void MemoryManager::initialize_physical_pages()
m_global_data.with([&](auto& global_data) {
// We assume that the physical page range is contiguous and doesn't contain huge gaps!
PhysicalAddress highest_physical_address;
#if ARCH(X86_64)
// On x86 LAPIC is at 0xfee00000 or a similar address. Round up to 0x100000000LL to cover variations.
highest_physical_address = PhysicalAddress { 0x100000000LL };
#endif
for (auto& range : global_data.used_memory_ranges) {
if (range.end.get() > highest_physical_address.get())
highest_physical_address = range.end;
@ -427,6 +431,15 @@ UNMAP_AFTER_INIT void MemoryManager::initialize_physical_pages()
highest_physical_address = range_end;
}
#if ARCH(X86_64)
// Map multiboot framebuffer
if ((multiboot_flags & MULTIBOOT_INFO_FRAMEBUFFER_INFO) && !multiboot_framebuffer_addr.is_null() && multiboot_framebuffer_type == MULTIBOOT_FRAMEBUFFER_TYPE_RGB) {
PhysicalAddress multiboot_framebuffer_addr_end = multiboot_framebuffer_addr.offset(multiboot_framebuffer_height * multiboot_framebuffer_pitch);
if (multiboot_framebuffer_addr_end > highest_physical_address)
highest_physical_address = multiboot_framebuffer_addr_end;
}
#endif
// Calculate how many total physical pages the array will have
m_physical_page_entries_count = PhysicalAddress::physical_page_index(highest_physical_address.get()) + 1;
VERIFY(m_physical_page_entries_count != 0);