| // We don't want it inlined because we specifically want the stack frame␊ |
| // pointer to be as high as possible and the hi_multiboot function␊ |
| // copies multiboot_info onto its stack.␊ |
| uint32_t hi_multiboot(int multiboot_magic, struct multiboot_info *mi_orig);␊ |
| uint64_t hi_multiboot(int multiboot_magic, struct multiboot_info *mi_orig);␊ |
| // prototype dochainload for the same reason.␊ |
| void dochainload();␊ |
| ␊ |
|
| int multiboot_get_ramdisk_info(int biosdev, struct driveInfo *dip);␊ |
| static long multiboot_LoadExtraDrivers(FileLoadDrivers_t FileLoadDrivers_p);␊ |
| ␊ |
| // Starts off in the multiboot context 1 MB high but eventually gets into low memory␊ |
| // and winds up with a bootdevice in eax which is all that boot() wants␊ |
| // This lets the stack pointer remain very high.␊ |
| // If we were to call boot directly from multiboot then the whole multiboot_info␊ |
| // would be on the stack which would possibly be using way too much stack.␊ |
| void multiboot_to_boot(int multiboot_magic, struct multiboot_info *mi_orig)␊ |
| {␊ |
| ␉uint32_t bootdevice = hi_multiboot(multiboot_magic, mi_orig);␊ |
| ␉if(bootdevice != BAD_BOOT_DEVICE)␊ |
| ␉{␊ |
| ␉␉// boot only returns to do a chain load.␊ |
| ␉␉for(;;)␊ |
| ␉␉{ // NOTE: boot only uses the last byte (the drive number)␊ |
| ␉␉␉common_boot(bootdevice);␊ |
| ␉␉␉if(chainbootflag)␊ |
| ␉␉␉␉chainLoad();␊ |
| ␉␉␉else␊ |
| ␉␉␉␉waitThenReload();␊ |
| ␉␉}␊ |
| ␉}␊ |
| ␉// Avoid returning to high-memory address which isn't valid in the segment␊ |
| ␉// we are now in.␊ |
| ␉// Calling sleep() ensures the user ought to be able to use Ctrl+Alt+Del␊ |
| ␉// because the BIOS will have interrupts on.␊ |
| ␉for(;;)␊ |
| ␉␉sleep(10);␊ |
| ␉// NOTE: *IF* we needed to return we'd have to fix up our return address to␊ |
| ␉// be in low memory using the same trick as below.␊ |
| ␉// However, there doesn't seem to be any point in returning to assembly␊ |
| ␉// particularly when the remaining code merely halts the processor.␊ |
| }␊ |
| ␊ |
| void chainLoad()␊ |
| {␊ |
| /* TODO: We ought to load the appropriate partition table, for example␊ |
|
| return mi_copy;␊ |
| }␊ |
| ␊ |
| // When we enter, we're actually 1 MB high.␊ |
| // Fortunately, memcpy is position independent, and it's all we need␊ |
| uint32_t hi_multiboot(int multiboot_magic, struct multiboot_info *mi_orig)␊ |
| {␊ |
| // Copy the multiboot info out of the way.␊ |
| // We can't bitch about the magic yet because printf won't work␊ |
| // because it contains an absolute location of putchar which␊ |
| // contains absolute locations to other things which eventually␊ |
| // makes a BIOS call from real mode which of course won't work␊ |
| // because we're stuck in extended memory at this point.␊ |
| struct multiboot_info *mi_p = copyMultibootInfo(multiboot_magic, mi_orig);␊ |
| ␊ |
| // Get us in to low memory so we can run everything␊ |
| ␊ |
| // We cannot possibly be more than 447k and copying extra won't really hurt anything␊ |
| // We use the address of the assembly entrypoint to get our starting location.␊ |
| memcpy(&boot2_sym, (char*)&boot2_sym + OFFSET_1MEG, BOOT2_MAX_LENGTH /* 447k */);␊ |
| ␊ |
| // This is a little assembler routine that returns to us in the correct selector␊ |
| // instead of the kernel selector we're running in now and at the correct␊ |
| // instruction pointer ( current minus 1 MB ). It does not fix our return␊ |
| // address nor does it fix the return address of our caller.␊ |
| continue_at_low_address();␊ |
| ␊ |
| // Now fix our return address.␊ |
| // JrCs: this macro should be rewritten because the code generated by XCode 4.x␊ |
| // change the value of the argument passed as parameter (multiboot_magic)␊ |
| // FIX_RETURN_ADDRESS_USING_FIRST_ARG(multiboot_magic);␊ |
| ␊ |
| // We can now do just about anything, including return to our caller correctly.␊ |
| // However, our caller must fix his return address if he wishes to return to␊ |
| // his caller and so on and so forth.␊ |
| ␊ |
| /* Zero the BSS and initialize malloc */␊ |
| initialize_runtime();␊ |
| ␊ |
| gMI = mi_p;␊ |
| ␊ |
| /* Set up a temporary bootArgs so we can call console output routines␊ |
| like printf that check the v_display. Note that we purposefully␊ |
| do not initialize anything else at this early stage.␊ |
| ␊ |
| We are reasonably sure we're already in text mode if GRUB booted us.␊ |
| This is the same assumption that initKernBootStruct makes.␊ |
| We could check the multiboot info I guess, but why bother?␊ |
| */␊ |
| boot_args temporaryBootArgsData;␊ |
| bzero(&temporaryBootArgsData, sizeof(boot_args));␊ |
| bootArgs = &temporaryBootArgsData;␊ |
| bootArgs->Video.v_display = VGA_TEXT_MODE;␊ |
| ␊ |
| // Install ramdisk and extra driver hooks␊ |
| p_get_ramdisk_info = &multiboot_get_ramdisk_info;␊ |
| p_ramdiskReadBytes = &multibootRamdiskReadBytes;␊ |
| LoadExtraDrivers_p = &multiboot_LoadExtraDrivers;␊ |
| ␊ |
| // Since we call multiboot ourselves, its return address will be correct.␊ |
| // That is unless it's inlined in which case it does not matter.␊ |
| uint32_t bootdevice = multiboot(multiboot_magic, mi_p);␊ |
| ␊ |
| // We're about to exit and temporaryBootArgs will no longer be valid␊ |
| bootArgs = NULL;␊ |
| return bootdevice;␊ |
| }␊ |
| ␊ |
| // This is the meat of our implementation. It grabs the boot device from␊ |
| // the multiboot_info and returns it as is. If it fails it returns␊ |
| // BAD_BOOT_DEVICE. We can call an awful lot of libsa and libsaio but␊ |
|
| return bootdevice;␊ |
| }␊ |
| ␊ |
| // When we enter, we're actually 1 MB high.␊ |
| // Fortunately, memcpy is position independent, and it's all we need␊ |
| uint64_t hi_multiboot(int multiboot_magic, struct multiboot_info *mi_orig)␊ |
| {␊ |
| // Copy the multiboot info out of the way.␊ |
| // We can't bitch about the magic yet because printf won't work␊ |
| // because it contains an absolute location of putchar which␊ |
| // contains absolute locations to other things which eventually␊ |
| // makes a BIOS call from real mode which of course won't work␊ |
| // because we're stuck in extended memory at this point.␊ |
| struct multiboot_info *mi_p = copyMultibootInfo(multiboot_magic, mi_orig);␊ |
| ␊ |
| // Get us in to low memory so we can run everything␊ |
| ␊ |
| // We cannot possibly be more than 447k and copying extra won't really hurt anything␊ |
| // We use the address of the assembly entrypoint to get our starting location.␊ |
| memcpy(&boot2_sym, (char*)&boot2_sym + OFFSET_1MEG, BOOT2_MAX_LENGTH /* 447k */);␊ |
| ␊ |
| // This is a little assembler routine that returns to us in the correct selector␊ |
| // instead of the kernel selector we're running in now and at the correct␊ |
| // instruction pointer ( current minus 1 MB ). It does not fix our return␊ |
| // address nor does it fix the return address of our caller.␊ |
| continue_at_low_address();␊ |
| ␊ |
| // Now fix our return address.␊ |
| // JrCs: this macro should be rewritten because the code generated by XCode 4.x␊ |
| // change the value of the argument passed as parameter (multiboot_magic)␊ |
| // FIX_RETURN_ADDRESS_USING_FIRST_ARG(multiboot_magic);␊ |
| ␊ |
| // We can now do just about anything, including return to our caller correctly.␊ |
| // However, our caller must fix his return address if he wishes to return to␊ |
| // his caller and so on and so forth.␊ |
| ␊ |
| /* Zero the BSS and initialize malloc */␊ |
| initialize_runtime();␊ |
| ␊ |
| gMI = mi_p;␊ |
| ␊ |
| /* Set up a temporary bootArgs so we can call console output routines␊ |
| like printf that check the v_display. Note that we purposefully␊ |
| do not initialize anything else at this early stage.␊ |
| ␊ |
| We are reasonably sure we're already in text mode if GRUB booted us.␊ |
| This is the same assumption that initKernBootStruct makes.␊ |
| We could check the multiboot info I guess, but why bother?␊ |
| */␊ |
| boot_args temporaryBootArgsData;␊ |
| bzero(&temporaryBootArgsData, sizeof(boot_args));␊ |
| bootArgs = &temporaryBootArgsData;␊ |
| bootArgs->Video.v_display = VGA_TEXT_MODE;␊ |
| ␊ |
| // Install ramdisk and extra driver hooks␊ |
| p_get_ramdisk_info = &multiboot_get_ramdisk_info;␊ |
| p_ramdiskReadBytes = &multibootRamdiskReadBytes;␊ |
| LoadExtraDrivers_p = &multiboot_LoadExtraDrivers;␊ |
| ␊ |
| // Since we call multiboot ourselves, its return address will be correct.␊ |
| // That is unless it's inlined in which case it does not matter.␊ |
| uint64_t bootdevice = multiboot( multiboot_magic, mi_orig); // mi_p);␊ |
| ␊ |
| ␉if(bootdevice != BAD_BOOT_DEVICE)␊ |
| ␉{␊ |
| ␉␉// boot only returns to do a chain load.␊ |
| ␉␉for(;;)␊ |
| ␉␉{ // NOTE: boot only uses the last byte (the drive number)␊ |
| ␉␉␉common_boot(bootdevice);␊ |
| ␉␉␉if(chainbootflag)␊ |
| ␉␉␉␉chainLoad();␊ |
| ␉␉␉else␊ |
| ␉␉␉␉waitThenReload();␊ |
| ␉␉}␊ |
| ␉}␊ |
| ␊ |
| // We're about to exit and temporaryBootArgs will no longer be valid␊ |
| bootArgs = NULL;␊ |
| return bootdevice;␊ |
| }␊ |
| ␊ |
| // Starts off in the multiboot context 1 MB high but eventually gets into low memory␊ |
| // and winds up with a bootdevice in eax which is all that boot() wants␊ |
| // This lets the stack pointer remain very high.␊ |
| // If we were to call boot directly from multiboot then the whole multiboot_info␊ |
| // would be on the stack which would possibly be using way too much stack.␊ |
| void multiboot_to_boot(int multiboot_magic, struct multiboot_info *mi_orig)␊ |
| {␊ |
| ␉hi_multiboot(multiboot_magic, mi_orig);␊ |
| ␊ |
| ␉// Avoid returning to high-memory address which isn't valid in the segment␊ |
| ␉// we are now in.␊ |
| ␉// Calling sleep() ensures the user ought to be able to use Ctrl+Alt+Del␊ |
| ␉// because the BIOS will have interrupts on.␊ |
| ␉for(;;)␊ |
| ␉␉sleep(10);␊ |
| ␉// NOTE: *IF* we needed to return we'd have to fix up our return address to␊ |
| ␉// be in low memory using the same trick as below.␊ |
| ␉// However, there doesn't seem to be any point in returning to assembly␊ |
| ␉// particularly when the remaining code merely halts the processor.␊ |
| ␊ |
| }␊ |
| ␊ |
| ///////////////////////////////////////////////////////////////////////////␊ |
| // Ramdisk and extra drivers code␊ |
| ␊ |
