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Some small improvements

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Philipp Oppermann
2015-12-09 15:25:24 +01:00
parent 75264e7cac
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posts/DRAFT-paging.md
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@@ -8,7 +8,7 @@ In this post we will create a paging module, which allows us to access and modif
TODO current Rust nightly version, link to github repo, etc.
## Paging
_Paging_ is a memory management scheme that separates virtual and physical memory. The address space is split into equal sized _pages_ and _page tables_ specify which virtual page points to which physical page. For an extensive paging introduction take a look at the paging chapter ([PDF][paging chapter]) of the [Three Easy Pieces] OS book.
_Paging_ is a memory management scheme that separates virtual and physical memory. The address space is split into equal sized _pages_ and _page tables_ specify which virtual page points to which physical frame. For an extensive paging introduction take a look at the paging chapter ([PDF][paging chapter]) of the [Three Easy Pieces] OS book.
[paging chapter]: http://pages.cs.wisc.edu/~remzi/OSTEP/vm-paging.pdf
[Three Easy Pieces]: http://pages.cs.wisc.edu/~remzi/OSTEP/
@@ -25,7 +25,7 @@ To translate an address, the CPU reads the P4 address from the CR3 register. The
![translation of virtual to physical addresses in 64 bit mode](/images/X86_Paging_64bit.svg)
The P4 entry points to a P3 table, where the next 9 bits of the address are used to select an entry. The P3 entry then points to a P2 table and the P2 entry points to a P1 table. The P1 entry, which is specified through bits 12–20, finally points to the physical page.
The P4 entry points to a P3 table, where the next 9 bits of the address are used to select an entry. The P3 entry then points to a P2 table and the P2 entry points to a P1 table. The P1 entry, which is specified through bits 12–20, finally points to the physical frame.
So let's create a Rust module for it! (TODO better transition)
@@ -737,7 +737,7 @@ We can also free the P1, P2, or even P3 table when the last entry is freed. But
_Spoiler_: There is an ugly bug in this function, which we will find in the next section.
## Testing it
## Testing and Bugfixing
To test it, we add a `test_paging` function in `memory/paging/mod.rs`:
```rust