stage1: return sorted memory map
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parent
21d33b6047
commit
326997330b
1 changed files with 14 additions and 6 deletions
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@ -1,6 +1,7 @@
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use crate::asm::{do_bios_int, BiosIntRegs};
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use core::cmp::Ordering;
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use core::mem::size_of;
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use core::ptr::slice_from_raw_parts_mut;
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#[derive(Eq, PartialEq)]
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#[repr(C)]
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@ -14,26 +15,28 @@ pub struct MemMapEntry {
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const SMAP: u32 = 0x534d4150;
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/// Use int15/e820 to detect the entire installed system memory.
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/// The entries are sorted by ascending start address.
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///
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/// ## Safety
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///
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/// `dest` must be aligned to at least 8 bytes, accessible from real mode,
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/// and have enough capacity to store the entire memory map. In practice,
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/// we use a 64 K segment, which should be way more than sufficient.
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pub unsafe fn read_bios_mmap(mut dest: *mut MemMapEntry) -> usize {
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pub unsafe fn read_bios_mmap(dest: *mut MemMapEntry) -> usize {
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let mut offset: u32 = 0;
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let mut count: usize = 0;
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debug_assert!((dest as *mut MemMapEntry as usize) < 0x10_0000);
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let mut pos = dest;
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loop {
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dest.as_mut().unwrap_unchecked().acpi30_ext = 1;
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pos.as_mut().unwrap_unchecked().acpi30_ext = 1;
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let regs = BiosIntRegs {
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eax: 0xe820,
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ecx: size_of::<MemMapEntry>() as u32,
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edx: SMAP,
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ebx: offset,
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edi: ((dest as usize) % 0x10) as u32,
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es: ((dest as usize) / 0x10) as u16,
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edi: ((pos as usize) % 0x10) as u32,
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es: ((pos as usize) / 0x10) as u16,
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..Default::default()
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};
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let result = match do_bios_int(0x15, regs) {
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@ -42,13 +45,13 @@ pub unsafe fn read_bios_mmap(mut dest: *mut MemMapEntry) -> usize {
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};
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if result.ecx < size_of::<MemMapEntry>() as u32 {
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dest.as_mut().unwrap_unchecked().acpi30_ext = 1;
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pos.as_mut().unwrap_unchecked().acpi30_ext = 1;
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}
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if result.eax != SMAP {
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break;
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}
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count += 1;
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dest = dest.add(1);
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pos = pos.add(1);
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if result.ebx == 0 {
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break;
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} else {
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@ -56,6 +59,11 @@ pub unsafe fn read_bios_mmap(mut dest: *mut MemMapEntry) -> usize {
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}
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}
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let mmap_mut = slice_from_raw_parts_mut(dest, count)
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.as_mut()
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.unwrap_unchecked();
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mmap_mut.sort_unstable();
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count
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}
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