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Move Stivale 2 header to separate module

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This commit is contained in:
Alex Kotov 2022-01-15 18:10:47 +05:00
parent 0aa8134fe8
commit 5cd0853e78
Signed by: kotovalexarian
GPG key ID: 553C0EBBEB5D5F08
4 changed files with 82 additions and 76 deletions
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3
examples/bootloader-stivale2-limine/.gitignore vendored
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@ -1,8 +1,9 @@
/*.c.d
/build-libkernaux/*
!/build-libkernaux/.keep
/image.iso
/main.c.d
/output.txt
/rootfs/boot/kernel
/rootfs/boot/limine-cd.bin

2
examples/bootloader-stivale2-limine/Makefile
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@ -56,7 +56,7 @@ CFLAGS = \
-MMD
# -pedantic \
OBJS = main.c.o # start.S.o
OBJS = main.c.o stivale2.c.o
test: run
$(DIFF) -a -Z $(EXPECTED) $(OUTPUT)

75
examples/bootloader-stivale2-limine/main.c
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@ -7,80 +7,7 @@
static void poweroff();
// We need to tell the stivale bootloader where we want our stack to be.
// We are going to allocate our stack as an array in .bss.
static uint8_t stack[8192];
// stivale2 uses a linked list of tags for both communicating TO the
// bootloader, or receiving info FROM it. More information about these tags
// is found in the stivale2 specification.
// stivale2 offers a runtime terminal service which can be ditched at any
// time, but it provides an easy way to print out to graphical terminal,
// especially during early boot.
// Read the notes about the requirements for using this feature below this
// code block.
static struct stivale2_header_tag_terminal terminal_hdr_tag = {
// All tags need to begin with an identifier and a pointer to the next tag.
.tag = {
// Identification constant defined in stivale2.h and the specification.
.identifier = STIVALE2_HEADER_TAG_TERMINAL_ID,
// If next is 0, it marks the end of the linked list of header tags.
.next = 0
},
// The terminal header tag possesses a flags field, leave it as 0 for now
// as it is unused.
.flags = 0
};
// We are now going to define a framebuffer header tag.
// This tag tells the bootloader that we want a graphical framebuffer instead
// of a CGA-compatible text mode. Omitting this tag will make the bootloader
// default to text mode, if available.
static struct stivale2_header_tag_framebuffer framebuffer_hdr_tag = {
// Same as above.
.tag = {
.identifier = STIVALE2_HEADER_TAG_FRAMEBUFFER_ID,
// Instead of 0, we now point to the previous header tag. The order in
// which header tags are linked does not matter.
.next = (uint64_t)&terminal_hdr_tag
},
// We set all the framebuffer specifics to 0 as we want the bootloader
// to pick the best it can.
.framebuffer_width = 0,
.framebuffer_height = 0,
.framebuffer_bpp = 0
};
// The stivale2 specification says we need to define a "header structure".
// This structure needs to reside in the .stivale2hdr ELF section in order
// for the bootloader to find it. We use this __attribute__ directive to
// tell the compiler to put the following structure in said section.
__attribute__((section(".stivale2hdr"), used))
static struct stivale2_header stivale_hdr = {
// The entry_point member is used to specify an alternative entry
// point that the bootloader should jump to instead of the executable's
// ELF entry point. We do not care about that so we leave it zeroed.
.entry_point = 0,
// Let's tell the bootloader where our stack is.
// We need to add the sizeof(stack) since in x86(_64) the stack grows
// downwards.
.stack = (uintptr_t)stack + sizeof(stack),
// Bit 1, if set, causes the bootloader to return to us pointers in the
// higher half, which we likely want since this is a higher half kernel.
// Bit 2, if set, tells the bootloader to enable protected memory ranges,
// that is, to respect the ELF PHDR mandated permissions for the executable's
// segments.
// Bit 3, if set, enables fully virtual kernel mappings, which we want as
// they allow the bootloader to pick whichever *physical* memory address is
// available to load the kernel, rather than relying on us telling it where
// to load it.
// Bit 4 disables a deprecated feature and should always be set.
.flags = (1 << 1) | (1 << 2) | (1 << 3) | (1 << 4),
// This header structure is the root of the linked list of header tags and
// points to the first one in the linked list.
.tags = (uintptr_t)&framebuffer_hdr_tag
};
uint8_t stack[8192];
// We will now write a helper function which will allow us to scan for tags
// that we want FROM the bootloader (structure tags).

78
examples/bootloader-stivale2-limine/stivale2.c Normal file
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@ -0,0 +1,78 @@
#include <stdint.h>
#include "stivale2.h"
// We need to tell the stivale bootloader where we want our stack to be.
// We are going to allocate our stack as an array in .bss.
extern uint8_t stack[8192];
// stivale2 uses a linked list of tags for both communicating TO the
// bootloader, or receiving info FROM it. More information about these tags
// is found in the stivale2 specification.
// stivale2 offers a runtime terminal service which can be ditched at any
// time, but it provides an easy way to print out to graphical terminal,
// especially during early boot.
// Read the notes about the requirements for using this feature below this
// code block.
static struct stivale2_header_tag_terminal terminal_hdr_tag = {
// All tags need to begin with an identifier and a pointer to the next tag.
.tag = {
// Identification constant defined in stivale2.h and the specification.
.identifier = STIVALE2_HEADER_TAG_TERMINAL_ID,
// If next is 0, it marks the end of the linked list of header tags.
.next = 0
},
// The terminal header tag possesses a flags field, leave it as 0 for now
// as it is unused.
.flags = 0
};
// We are now going to define a framebuffer header tag.
// This tag tells the bootloader that we want a graphical framebuffer instead
// of a CGA-compatible text mode. Omitting this tag will make the bootloader
// default to text mode, if available.
static struct stivale2_header_tag_framebuffer framebuffer_hdr_tag = {
// Same as above.
.tag = {
.identifier = STIVALE2_HEADER_TAG_FRAMEBUFFER_ID,
// Instead of 0, we now point to the previous header tag. The order in
// which header tags are linked does not matter.
.next = (uint64_t)&terminal_hdr_tag
},
// We set all the framebuffer specifics to 0 as we want the bootloader
// to pick the best it can.
.framebuffer_width = 0,
.framebuffer_height = 0,
.framebuffer_bpp = 0
};
// The stivale2 specification says we need to define a "header structure".
// This structure needs to reside in the .stivale2hdr ELF section in order
// for the bootloader to find it. We use this __attribute__ directive to
// tell the compiler to put the following structure in said section.
__attribute__((section(".stivale2hdr"), used))
static struct stivale2_header stivale_hdr = {
// The entry_point member is used to specify an alternative entry
// point that the bootloader should jump to instead of the executable's
// ELF entry point. We do not care about that so we leave it zeroed.
.entry_point = 0,
// Let's tell the bootloader where our stack is.
// We need to add the sizeof(stack) since in x86(_64) the stack grows
// downwards.
.stack = (uintptr_t)stack + sizeof(stack),
// Bit 1, if set, causes the bootloader to return to us pointers in the
// higher half, which we likely want since this is a higher half kernel.
// Bit 2, if set, tells the bootloader to enable protected memory ranges,
// that is, to respect the ELF PHDR mandated permissions for the executable's
// segments.
// Bit 3, if set, enables fully virtual kernel mappings, which we want as
// they allow the bootloader to pick whichever *physical* memory address is
// available to load the kernel, rather than relying on us telling it where
// to load it.
// Bit 4 disables a deprecated feature and should always be set.
.flags = (1 << 1) | (1 << 2) | (1 << 3) | (1 << 4),
// This header structure is the root of the linked list of header tags and
// points to the first one in the linked list.
.tags = (uintptr_t)&framebuffer_hdr_tag
};