RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-07-27 05:37:34 +00:00
Code Issues Activity Actions

Kernel/x86: Bake the Prekernel and the Kernel into one image

Browse source 
The new baked image is a Prekernel and a Kernel baked together now, so
essentially we no longer need to pass the Prekernel as -kernel and the
actual  kernel image as -initrd to QEMU, leaving the option to pass an
actual initrd or initramfs module later on with multiboot.
This commit is contained in:
Liav A 2023-03-24 20:31:53 +03:00 • committed by Jelle Raaijmakers
parent 2a1e58f8cc
commit 897c4e5145
10 changed files with 81 additions and 50 deletions
Download patch file Download diff file Expand all files Collapse all files

22
Kernel/Prekernel/CMakeLists.txt
View file

@ -8,14 +8,21 @@ set(SOURCES
)
if ("${SERENITY_ARCH}" STREQUAL "x86_64")
set(PREKERNEL_TARGET Prekernel64)
set(PREKERNEL_TARGET kernel_x86-64)
elseif("${SERENITY_ARCH}" STREQUAL "aarch64")
message(SEND_ERROR "Prekernel is not needed on aarch64 and should not be compiled!")
endif()
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static")
add_executable(${PREKERNEL_TARGET} ${SOURCES})
add_library(KernelObject OBJECT IMPORTED)
set_property(TARGET KernelObject PROPERTY
IMPORTED_OBJECTS ${CMAKE_CURRENT_BINARY_DIR}/../Kernel.o
)
add_executable(${PREKERNEL_TARGET} ${SOURCES} $<TARGET_OBJECTS:KernelObject>)
add_dependencies(${PREKERNEL_TARGET} Kernel)
target_compile_options(${PREKERNEL_TARGET} PRIVATE -no-pie -fno-pic -fno-threadsafe-statics)
target_link_options(${PREKERNEL_TARGET} PRIVATE LINKER:-T ${CMAKE_CURRENT_SOURCE_DIR}/linker.ld -nostdlib LINKER:--no-pie)
@ -27,13 +34,20 @@ elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang$")
target_link_libraries(${PREKERNEL_TARGET} PRIVATE clang_rt.builtins)
endif()
if ("${SERENITY_ARCH}" STREQUAL "x86_64")
set(ELF_OBJCOPY_TARGET "elf32-i386")
elseif("${SERENITY_ARCH}" STREQUAL "aarch64")
message(SEND_ERROR "Prekernel is not needed on aarch64 and should not be compiled!")
endif()
add_custom_command(
TARGET ${PREKERNEL_TARGET} POST_BUILD
COMMAND ${CMAKE_OBJCOPY} -O elf32-i386 ${CMAKE_CURRENT_BINARY_DIR}/${PREKERNEL_TARGET} ${CMAKE_CURRENT_BINARY_DIR}/Prekernel
COMMAND ${CMAKE_OBJCOPY} -O ${ELF_OBJCOPY_TARGET} ${CMAKE_CURRENT_BINARY_DIR}/${PREKERNEL_TARGET} ${CMAKE_CURRENT_BINARY_DIR}/../Kernel
BYPRODUCTS ${CMAKE_CURRENT_BINARY_DIR}/Prekernel
)
install(FILES "${CMAKE_CURRENT_BINARY_DIR}/Prekernel" DESTINATION boot)
install(FILES "${CMAKE_CURRENT_BINARY_DIR}/../Kernel" DESTINATION boot)
# Remove options which the Prekernel environment doesn't support.
get_target_property(PREKERNEL_TARGET_OPTIONS ${PREKERNEL_TARGET} COMPILE_OPTIONS)

5
Kernel/Prekernel/Prekernel.h
View file

@ -41,8 +41,11 @@ struct [[gnu::packed]] BootInfo {
u32 multiboot_flags;
u64 multiboot_memory_map;
u32 multiboot_memory_map_count;
u64 multiboot_modules;
u64 multiboot_modules_physical_ptr;
u32 multiboot_modules_count;
u32 multiboot_module_ramdisk_physical_start;
u32 multiboot_module_ramdisk_physical_end;
u32 multiboot_module_ramdisk_physical_string_addr;
u64 multiboot_framebuffer_addr;
u32 multiboot_framebuffer_pitch;
u32 multiboot_framebuffer_width;

27
Kernel/Prekernel/init.cpp
View file

@ -27,6 +27,9 @@ extern "C" [[noreturn]] void __stack_chk_fail();
extern "C" u8 start_of_prekernel_image[];
extern "C" u8 end_of_prekernel_image[];
extern "C" u8 _binary_Kernel_standalone_start[];
extern "C" u8 end_of_prekernel_image_after_kernel_image[];
extern "C" u8 gdt64ptr[];
extern "C" u16 code64_sel;
extern "C" u64 boot_pml4t[512];
@ -76,12 +79,7 @@ u64 generate_secure_seed();
extern "C" [[noreturn]] void init()
{
if (multiboot_info_ptr->mods_count < 1)
halt();
multiboot_module_entry_t* kernel_module = (multiboot_module_entry_t*)(FlatPtr)multiboot_info_ptr->mods_addr;
u8* kernel_image = (u8*)(FlatPtr)kernel_module->start;
u8* kernel_image = _binary_Kernel_standalone_start;
// copy the ELF header and program headers because we might end up overwriting them
ElfW(Ehdr) kernel_elf_header = *(ElfW(Ehdr)*)kernel_image;
ElfW(Phdr) kernel_program_headers[16];
@ -89,8 +87,8 @@ extern "C" [[noreturn]] void init()
halt();
__builtin_memcpy(kernel_program_headers, kernel_image + kernel_elf_header.e_phoff, sizeof(ElfW(Phdr)) * kernel_elf_header.e_phnum);
FlatPtr kernel_physical_base = 0x200000;
FlatPtr default_kernel_load_base = KERNEL_MAPPING_BASE + 0x200000;
FlatPtr kernel_physical_base = (FlatPtr)kernel_image;
FlatPtr default_kernel_load_base = KERNEL_MAPPING_BASE + kernel_physical_base;
FlatPtr kernel_load_base = default_kernel_load_base;
@ -168,9 +166,6 @@ extern "C" [[noreturn]] void init()
__builtin_memset((u8*)kernel_load_base + kernel_program_header.p_vaddr + kernel_program_header.p_filesz, 0, kernel_program_header.p_memsz - kernel_program_header.p_filesz);
}
multiboot_info_ptr->mods_count--;
multiboot_info_ptr->mods_addr += sizeof(multiboot_module_entry_t);
auto adjust_by_mapping_base = [kernel_mapping_base](auto ptr) {
return (decltype(ptr))((FlatPtr)ptr + kernel_mapping_base);
};
@ -194,8 +189,16 @@ extern "C" [[noreturn]] void init()
info.multiboot_flags = multiboot_info_ptr->flags;
info.multiboot_memory_map = adjust_by_mapping_base((FlatPtr)multiboot_info_ptr->mmap_addr);
info.multiboot_memory_map_count = multiboot_info_ptr->mmap_length / sizeof(multiboot_memory_map_t);
info.multiboot_modules = adjust_by_mapping_base((FlatPtr)multiboot_info_ptr->mods_addr);
info.multiboot_modules_physical_ptr = (FlatPtr)multiboot_info_ptr->mods_addr;
info.multiboot_modules_count = multiboot_info_ptr->mods_count;
if (info.multiboot_modules_count > 0) {
auto* entry = reinterpret_cast<multiboot_module_entry*>(multiboot_info_ptr->mods_addr);
info.multiboot_module_ramdisk_physical_start = entry->start;
info.multiboot_module_ramdisk_physical_end = entry->end;
info.multiboot_module_ramdisk_physical_string_addr = entry->string_addr;
}
if ((multiboot_info_ptr->flags & MULTIBOOT_INFO_FRAMEBUFFER_INFO) != 0) {
info.multiboot_framebuffer_addr = multiboot_info_ptr->framebuffer_addr;
info.multiboot_framebuffer_pitch = multiboot_info_ptr->framebuffer_pitch;

9
Kernel/Prekernel/linker.ld
View file

@ -44,4 +44,13 @@ SECTIONS
} :bss
end_of_prekernel_image = .;
.Kernel_image ALIGN(4K) : AT (ADDR(.Kernel_image))
{
_binary_Kernel_standalone_start = .;
KEEP(*(.Kernel_image))
}
end_of_prekernel_image_after_kernel_image = .;
}