// this func calculate the number of frames
// require for the ram and then acc to that
// create no. of frames which will be required for it
// and also mark the space which is preoccupied
// by the kernel
void init_mm(u32int ram_sz_bytes)
{
// create a bitmap for the record
// which blocks is allocated
// and which isn't
initFrames(ram_sz_bytes);
// right now bit is full of zero
// means nothing is allocated yet
// so we have place one to show that
// kernel is here you can't allocate
// here
allocate_kernel();
}
/**
* Load an x86 Linux kernel.
*
* @param loader Loader internal data.
*/
__noreturn void linux_arch_load(linux_loader_t *loader)
{
linux_params_t *params;
size_t cmdline_size, setup_size, load_size;
char *cmdline;
void *virt;
phys_ptr_t phys, initrd_max;
list_t memory_map;
status_t ret;
static_assert(sizeof(linux_params_t) == PAGE_SIZE);
static_assert(offsetof(linux_params_t, hdr) == LINUX_HEADER_OFFSET);
// Allocate memory for the parameters data (the "zero page").
params = memory_alloc(sizeof(linux_params_t), 0, 0x10000, 0x90000, MEMORY_TYPE_RECLAIMABLE, 0, NULL);
memset(params, 0, sizeof(*params));
// Read in the kernel header.
ret = fs_read(loader->kernel, ¶ms->hdr, sizeof(params->hdr), offsetof(linux_params_t, hdr));
if (ret != STATUS_SUCCESS)
boot_error("Error reading kernel header: %pS", ret);
// Start populating required fields in the header. Don't set heap_end_ptr or
// the CAN_USE_HEAP flag, as these appear to only be required by the 16-bit
// entry point which we do not use.
params->hdr.type_of_loader = 0xff;
// Calculate the maximum command line size.
cmdline_size = (params->hdr.version >= 0x0206) ? params->hdr.cmdline_size : 255;
if (strlen(loader->cmdline) > cmdline_size)
boot_error("Kernel command line is too long");
// Allocate memory for command line.
cmdline_size = round_up(cmdline_size + 1, PAGE_SIZE);
cmdline = memory_alloc(cmdline_size, 0, 0x10000, 0x90000, MEMORY_TYPE_RECLAIMABLE, 0, NULL);
strncpy(cmdline, loader->cmdline, cmdline_size);
cmdline[cmdline_size] = 0;
params->hdr.cmd_line_ptr = (uint32_t)((ptr_t)cmdline);
// Determine the setup code size.
if (params->hdr.setup_sects)
setup_size = (params->hdr.setup_sects + 1) * 512;
else
setup_size = 5 * 512;
// Load size is total file size minus setup size.
load_size = loader->kernel->size - setup_size;
// Allocate memory for the kernel image.
virt = allocate_kernel(params, load_size, &phys);
if (!virt)
boot_error("Insufficient memory available for kernel image");
params->hdr.code32_start = phys + params->hdr.code32_start - LINUX_BZIMAGE_ADDR;
// Read in the kernel image.
ret = fs_read(loader->kernel, virt, load_size, setup_size);
if (ret != STATUS_SUCCESS)
boot_error("Error reading kernel image: %pS", ret);
// Load in the initrd(s).
if (loader->initrd_size) {
initrd_max = (params->hdr.version >= 0x0203)
? params->hdr.initrd_addr_max
: 0x37ffffff;
// It is recommended that the initrd be loaded as high as possible.
virt = memory_alloc(
round_up(loader->initrd_size, PAGE_SIZE), 0,
0x100000, initrd_max + 1, MEMORY_TYPE_MODULES, MEMORY_ALLOC_HIGH, &phys);
dprintf(
"linux: loading initrd to 0x%" PRIxPHYS " (size: 0x%zx, max: 0x%" PRIxPHYS ")\n",
phys, loader->initrd_size, initrd_max);
linux_initrd_load(loader, virt);
params->hdr.ramdisk_image = phys;
params->hdr.ramdisk_size = loader->initrd_size;
}
// Set the video mode.
linux_video_set(loader);
// Perform pre-boot tasks.
loader_preboot();
// Get the final memory map and print it out for informational purposes.
// Note that the memory_finalize() is necessary on EFI in order to free up
// any internal allocations in the EFI memory map so that they will be free
// to the kernel.
dprintf("linux: final physical memory map:\n");
memory_finalize(&memory_map);
memory_map_dump(&memory_map);
// Get platform code to do any setup it needs and enter the kernel.
// For BIOS, this will obtain information usually obtained by the real-mode
// bootstrap when using the 16-bit boot protocol, then jump to the 32-bit
// entry point. For EFI, this will enter the kernel using the handover
// protocol.
linux_platform_load(loader, params);
}