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boot: STACK_SIZE is 1024 now

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since d594aa0277 (diff-0af1468d3dc7f373d70011eda7be1592)
This commit is contained in:
Alexander Kuleshov 2017-09-12 00:53:18 +06:00
parent 96afdad6f4
commit 220d3378f7
2 changed files with 6 additions and 4 deletions
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2
Booting/linux-bootstrap-1.md
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@ -432,7 +432,7 @@ Field name: loadflags
functionality will be disabled.
```
If the `CAN_USE_HEAP` bit is set, we put `heap_end_ptr` into `dx` (which points to `_end`) and add `STACK_SIZE` (minimum stack size, `512` bytes) to it. After this, if `dx` is not carried (it will not be carried, `dx = _end + 512`), jump to label `2` (as in the previous case) and make a correct stack.
If the `CAN_USE_HEAP` bit is set, we put `heap_end_ptr` into `dx` (which points to `_end`) and add `STACK_SIZE` (minimum stack size, `1024` bytes) to it. After this, if `dx` is not carried (it will not be carried, `dx = _end + 1024`), jump to label `2` (as in the previous case) and make a correct stack.
![stack](http://oi62.tinypic.com/dr7b5w.jpg)

8
Booting/linux-bootstrap-2.md
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@ -329,10 +329,12 @@ First of all `init_heap` checks the [`CAN_USE_HEAP`](https://github.com/torvalds
or in other words `stack_end = esp - STACK_SIZE`.
Then there is the `heap_end` calculation:
```c
heap_end = (char *)((size_t)boot_params.hdr.heap_end_ptr + 0x200);
```C
heap_end = (char *)((size_t)boot_params.hdr.heap_end_ptr + 0x200);
```
which means `heap_end_ptr` or `_end` + `512`(`0x200h`). The last check is whether `heap_end` is greater than `stack_end`. If it is then `stack_end` is assigned to `heap_end` to make them equal.
which means `heap_end_ptr` or `_end` + `512` (`0x200h`). The last check is whether `heap_end` is greater than `stack_end`. If it is then `stack_end` is assigned to `heap_end` to make them equal.
Now the heap is initialized and we can use it using the `GET_HEAP` method. We will see how it is used, how to use it and how it is implemented in the next posts.