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Kernel: Allocate user physical pages instead of supervisor ones for DMA

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We are limited on the amount of supervisor pages we can allocate, so
don't allocate from that pool. Supervisor pages are always below 16 MiB
barrier so using those was crucial when we used devices like the ISA
SoundBlaster 16 card, because that device required very low physical
addresses to be used.
This commit is contained in:
Liav A 2022-07-08 19:17:57 +03:00 committed by Andreas Kling
parent b22149601a
commit 37b4133c51
Notes: sideshowbarker 2024-07-17 08:57:43 +09:00 
Author: https://github.com/supercomputer7
Commit: https://github.com/SerenityOS/serenity/commit/37b4133c51
Pull-request: https://github.com/SerenityOS/serenity/pull/14522
Reviewed-by: https://github.com/awesomekling
1 changed files with 1 additions and 1 deletions
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2
Kernel/Memory/MemoryManager.cpp
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@ -791,7 +791,7 @@ ErrorOr<NonnullOwnPtr<Memory::Region>> MemoryManager::allocate_dma_buffer_page(S
ErrorOr<NonnullOwnPtr<Memory::Region>> MemoryManager::allocate_dma_buffer_pages(size_t size, StringView name, Memory::Region::Access access, NonnullRefPtrVector<Memory::PhysicalPage>& dma_buffer_pages)
{
VERIFY(!(size % PAGE_SIZE));
dma_buffer_pages = TRY(allocate_contiguous_supervisor_physical_pages(size));
dma_buffer_pages = TRY(allocate_contiguous_user_physical_pages(size));
// Do not enable Cache for this region as physical memory transfers are performed (Most architectures have this behaviour by default)
return allocate_kernel_region(dma_buffer_pages.first().paddr(), size, name, access, Region::Cacheable::No);
}