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@@ -4,9 +4,9 @@ Kernel booting process. Part 3.
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Video mode initialization and transition to protected mode
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Video mode initialization and transition to protected mode
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-This is the third part of the `Kernel booting process` series. In the previous [part](https://github.com/0xAX/linux-insides/blob/master/Booting/linux-bootstrap-2.md#kernel-booting-process-part-2), we stopped right before the call of the `set_video` routine from the [main.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/main.c#L181). We will see video mode initialization in the kernel setup code, preparation before switching into the protected mode and transition into it in this part.
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+This is the third part of the `Kernel booting process` series. In the previous [part](linux-bootstrap-2.md#kernel-booting-process-part-2), we stopped right before the call of the `set_video` routine from the [main.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/main.c#L181). We will see video mode initialization in the kernel setup code, preparation before switching into the protected mode and transition into it in this part.
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-**NOTE** If you don't know anything about protected mode, you can find some information about it in the previous [part](https://github.com/0xAX/linux-insides/blob/master/Booting/linux-bootstrap-2.md#protected-mode). Also there are a couple of [links](https://github.com/0xAX/linux-insides/blob/master/Booting/linux-bootstrap-2.md#links) which can help you.
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+**NOTE** If you don't know anything about protected mode, you can find some information about it in the previous [part](linux-bootstrap-2.md#protected-mode). Also there are a couple of [links](linux-bootstrap-2.md#links) which can help you.
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As i wrote above, we will start from the `set_video` function which defined in the [arch/x86/boot/video.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/video.c#L315) source code file. We can see that it starts with getting of video mode from the `boot_params.hdr` structure:
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As i wrote above, we will start from the `set_video` function which defined in the [arch/x86/boot/video.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/video.c#L315) source code file. We can see that it starts with getting of video mode from the `boot_params.hdr` structure:
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@@ -118,7 +118,7 @@ static inline bool heap_free(size_t n)
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}
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}
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```
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```
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-which subtracts value of the `HEAP` from the `heap_end` (we calculated it in the previous [part](https://github.com/0xAX/linux-insides/blob/master/Booting/linux-bootstrap-2.md)) and returns 1 if there is enough memory for `n`.
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+which subtracts value of the `HEAP` from the `heap_end` (we calculated it in the previous [part](linux-bootstrap-2.md)) and returns 1 if there is enough memory for `n`.
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That's all. Now we have simple API for heap and can setup video mode.
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That's all. Now we have simple API for heap and can setup video mode.
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@@ -351,7 +351,7 @@ where we can see - 16-bit length of IDT and 32-bit pointer to it (More details a
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Setup Global Descriptor Table
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Setup Global Descriptor Table
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-The next point is setup of the Global Descriptor Table (GDT). We can see `setup_gdt` function which setups GDT (you can read about it in the [Kernel booting process. Part 2.](https://github.com/0xAX/linux-insides/blob/master/Booting/linux-bootstrap-2.md#protected-mode)). There is definition of the `boot_gdt` array in this function, which contains definition of the three segments:
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+The next point is setup of the Global Descriptor Table (GDT). We can see `setup_gdt` function which setups GDT (you can read about it in the [Kernel booting process. Part 2.](linux-bootstrap-2.md#protected-mode)). There is definition of the `boot_gdt` array in this function, which contains definition of the three segments:
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```C
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```C
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static const u64 boot_gdt[] __attribute__((aligned(16))) = {
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static const u64 boot_gdt[] __attribute__((aligned(16))) = {
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@@ -389,7 +389,7 @@ int main(void)
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Technically structure which contains one `int` field, must be 4 bytes, but here `aligned` structure will be 16 bytes:
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Technically structure which contains one `int` field, must be 4 bytes, but here `aligned` structure will be 16 bytes:
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```
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```
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-$ gcc test.c -o test && ./test
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+$ gcc test.c -o test && test
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Not aligned - 4
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Not aligned - 4
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Aligned - 16
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Aligned - 16
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```
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```
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@@ -421,7 +421,7 @@ in binary. Let's try to understand what every bit means. We will go through all
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* 101 - segment type execute/read/
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* 101 - segment type execute/read/
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* 1 - accessed bit
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* 1 - accessed bit
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-You can know more about every bit in the previous [post](https://github.com/0xAX/linux-insides/blob/master/Booting/linux-bootstrap-2.md) or in the [Intel® 64 and IA-32 Architectures Software Developer’s Manuals 3A](http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html).
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+You can know more about every bit in the previous [post](linux-bootstrap-2.md) or in the [Intel® 64 and IA-32 Architectures Software Developer’s Manuals 3A](http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html).
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After this we get length of GDT with:
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After this we get length of GDT with:
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@@ -538,4 +538,4 @@ Links
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* [A20](http://en.wikipedia.org/wiki/A20_line)
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* [A20](http://en.wikipedia.org/wiki/A20_line)
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* [GCC designated inits](https://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Designated-Inits.html)
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* [GCC designated inits](https://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Designated-Inits.html)
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* [GCC type attributes](https://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html)
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* [GCC type attributes](https://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html)
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-* [Previous part](https://github.com/0xAX/linux-insides/blob/master/Booting/linux-bootstrap-2.md)
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+* [Previous part](linux-bootstrap-2.md)
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