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The boot loader MMU can now also unmap/free memory - this is needed if the frame

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buffer resolution changes during execution (ie. if the boot menu is opened late
and you change the video mode).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12233 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2005-04-04 16:10:09 +00:00
parent 8b618fc01c
commit 4d5f980d99
1 changed files with 42 additions and 3 deletions
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45
src/kernel/boot/platform/bios_ia32/mmu.cpp
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@ -127,6 +127,20 @@ add_page_table(addr_t base)
}
static void
unmap_page(addr_t virtualAddress)
{
TRACE(("unmap_page(virtualAddress = %p)\n", (void *)virtualAddress));
if (virtualAddress < KERNEL_BASE)
panic("unmap_page: asked to unmap invalid page %p!\n", (void *)virtualAddress);
sPageTable[(virtualAddress % (B_PAGE_SIZE * 1024)) / B_PAGE_SIZE] = 0;
asm volatile("invlpg (%0)" : : "r" (virtualAddress));
}
/** Creates an entry to map the specified virtualAddress to the given
* physicalAddress.
* If the mapping goes beyond the current page table, it will allocate
@ -158,8 +172,6 @@ map_page(addr_t virtualAddress, addr_t physicalAddress, uint32 flags)
sPageTable[(virtualAddress % (B_PAGE_SIZE * 1024)) / B_PAGE_SIZE] = physicalAddress | flags;
asm volatile("invlpg (%0)" : : "r" (virtualAddress));
// should not be necessary (as we can't free memory yet),
// but it won't hurt either :)
}
@ -321,10 +333,37 @@ mmu_allocate(void *virtualAddress, size_t size)
}
/** This will unmap the allocated chunk of memory from the virtual
* address space. It might not actually free memory (as its implementation
* is very simple), but it might.
*/
extern "C" void
mmu_free(void *virtualAddress, size_t size)
{
// ToDo: implement freeing a region (do we have to?)
TRACE(("mmu_free(virtualAddress = %p, size: %ld)\n", virtualAddress, size));
addr_t address = (addr_t)virtualAddress;
size = (size + B_PAGE_SIZE - 1) / B_PAGE_SIZE;
// get number of pages to map
// is the address within the valid range?
if (address < KERNEL_BASE
|| address + size >= KERNEL_BASE + kMaxKernelSize) {
panic("mmu_free: asked to unmap out of range region (%p, size %lx)\n",
address, size);
}
// unmap all pages within the range
for (uint32 i = 0; i < size; i++) {
unmap_page(address);
address += B_PAGE_SIZE;
}
if (address == sNextVirtualAddress) {
// we can actually reuse the virtual address space
sNextVirtualAddress -= size;
}
}