/* At entry, the processor is in 16 bit real mode and the code is being * executed from an address it was not linked to. Code must be pic and * 32 bit sensitive until things are fixed up. * * Also be very careful as the stack is at the rear end of the interrupt * table so using a noticeable amount of stack space is a no-no. */ /* Define DELAYED_INT when NO_DELAYED_INT is not defined. * This allows positive tests instead of tests that contain * double negatives, and become confusing. */ #ifndef NO_DELAYED_INT #define DELAYED_INT #endif /* We need some unique magic ID, if we defer startup thru the INT18H or INT19H * handler. This way, we can check if we have already been installed. */ #ifndef MAGIC #define MAGIC 0xE44C #endif /* Hook into INT18H or INT19H handler */ #ifdef BOOT_INT18H #define BOOT_INT 0x18 #else #define BOOT_INT 0x19 #endif #define BOOT_INT_VEC BOOT_INT*4 #define SCRATCHVEC 0x300 /* Prefix exit codes. We store these on the stack so that we will * know how to return control to the BIOS when Etherboot exits. */ #define EXIT_VIA_LRET 0x0 #define EXIT_VIA_INT_18 0x1 #define EXIT_VIA_BOOT_INT 0x2 .text .code16 .arch i386 .org 0 .section ".prefix", "ax", @progbits .globl _prefix _prefix: .word 0xAA55 /* BIOS extension signature */ size: .byte 0 /* number of 512 byte blocks */ /* = number of 256 word blocks */ /* filled in by makerom program */ jmp over /* skip over checksum */ .byte 0 /* checksum */ jmp legacyentry /* alternate entry point +6 */ /* used by mknbi-rom */ #ifdef PCI_PNP_HEADER mfgstr: .asciz "Etherboot" #ifdef PXE_EXPORT .org 0x16 .word UNDIROMID - _prefix #endif /* PXE_EXPORT */ .org 0x18 .word PCI - _prefix .word PnP - _prefix PCI: .ascii "PCIR" .word 0x0000 /* vendor ID, filled in by makerom */ .word 0x0000 /* device ID, filled in by makerom */ .word 0x0000 /* pointer to vital product data */ .word 0x0018 /* PCI data structure length */ .byte 0x00 /* PCI data structure revision */ .byte 0x02 /* Device Base Type code */ .byte 0x00 /* Device Sub-Type code */ .byte 0x00 /* Device Interface Type code */ .word 0x0000 /* Image length same as offset 02h */ .word 0x0001 /* revision level of code/data */ .byte 0x00 /* code type */ .byte 0x80 /* indicator (last PCI data structure) */ .word 0x0000 /* reserved */ PnP: .ascii "$PnP" .byte 0x01 /* structure revision */ .byte 0x02 /* length (in 16 byte increments) */ .word 0x0000 /* offset of next header */ .byte 0x00 /* Reserved */ .byte 0x00 /* checksum filled by makerom */ .long 0x00000000 /* Device identifier */ .word mfgstr - _prefix .word 0x0 /* pointer to product name */ /* filled by makerom */ .byte 0x02 /* Device Base Type code */ .byte 0x00 /* Device Sub-Type code */ .byte 0x00 /* Device Interface Type code */ .byte 0x14 /* device indicator */ .word 0x0000 /* boot connection vector */ .word 0x0000 /* disconnect vector */ .word pnpentry - _prefix .word 0x0000 /* reserved */ .word 0x0000 /* static resource information vector */ #ifdef PXE_EXPORT UNDIROMID: .ascii "UNDI" .byte UNDIROMID_end - UNDIROMID /* length of structure */ .byte 0 /* Checksum */ .byte 0 /* Structure revision */ .byte 0,1,2 /* PXE version 2.1.0 */ .word UNDILoader - _prefix /* Offset to loader routine */ .word UNDIStackSize /* Stack segment size */ .word UNDIDataSize /* Data segment size */ .word UNDICodeSize /* Code segment size */ .ascii "PCIR" /* The code segment contains our pxe_stack_t plus the PXE and * RM callback interfaces. We don't actually use a data * segment, but we put a nonzero value here to avoid confusing * things. 16k of stack space should be enough. * * When we claim our own memory, we fill out the data segment * with the address and size of the real-mode stack, so that * NBPs will free that area of memory for us. When the UNDI * loader is used to initialise us, we will never need a * real-mode stack because we will only ever be called via the * PXE API, hence our stack is already in base memory. */ .equ UNDICodeSize, _pxe_stack_size .equ UNDIDataSize, _real_mode_stack_size .equ UNDIStackSize, _real_mode_stack_size UNDIROMID_end: #endif /* PXE_EXPORT */ #endif /* PCI_PNP_HEADER */ /* * Explicitly specify DI is wrt ES to avoid problems with some BIOSes * Discovered by Eric Biederman * In addition, some BIOSes don't point DI to the string $PnP so * we need another #define to take care of that. */ over: #ifdef DEBUG_ROMPREFIX call print_bcv #endif /* Omit this test for ISA cards anyway */ #ifdef PCI_PNP_HEADER /* Accept old name too for backward compatibility */ #if !defined(BBS_BUT_NOT_PNP_COMPLIANT) && !defined(PNP_BUT_NOT_BBS_COMPLIANT) cmpw $'$'+'P'*256,%es:0(%di) jne notpnp cmpw $'n'+'P'*256,%es:2(%di) jne notpnp #endif /* BBS_BUT_NOT_PNP_COMPLIANT */ movw $0x20,%ax lret #endif /* PCI_PNP_HEADER */ notpnp: #ifdef DEBUG_ROMPREFIX call print_notpnp #endif #ifdef DELAYED_INT pushw %ax pushw %ds xorw %ax,%ax movw %ax,%ds /* access first 64kB segment */ movw SCRATCHVEC+4, %ax /* check if already installed */ cmpw $MAGIC, %ax /* check magic word */ jz installed movw BOOT_INT_VEC, %ax /* hook into INT18H or INT19H */ movw %ax, SCRATCHVEC movw BOOT_INT_VEC+2, %ax movw %ax, SCRATCHVEC+2 movw $start_int - _prefix, %ax movw %ax, BOOT_INT_VEC movw %cs,%ax movw %ax, BOOT_INT_VEC+2 movw $MAGIC, %ax /* set magic word */ movw %ax, SCRATCHVEC+4 #ifdef DEBUG_ROMPREFIX call print_installed #endif installed: popw %ds popw %ax movw $0x20,%ax lret start_int: /* clobber magic id, so that we will */ #ifdef DEBUG_ROMPREFIX call print_start_int #endif xorw %ax,%ax /* not inadvertendly end up in an */ movw %ax,%ds /* endless loop */ movw %ax, SCRATCHVEC+4 movw SCRATCHVEC+2, %ax /* restore original INT19h handler */ movw %ax, BOOT_INT_VEC+2 movw SCRATCHVEC, %ax movw %ax, BOOT_INT_VEC pushl %eax /* padding */ pushw $EXIT_VIA_BOOT_INT jmp invoke #endif /* DELAYED_INT */ legacyentry: #ifdef DEBUG_ROMPREFIX call print_legacyentry #endif pushw $EXIT_VIA_LRET jmp invoke #ifdef PCI_PNP_HEADER pnpentry: #ifdef DEBUG_ROMPREFIX call print_bev #endif pushl %eax /* padding */ pushw $EXIT_VIA_INT_18 jmp invoke #endif /* PCI_PNP_HEADER */ invoke: /* Store ROM segment and size on stack */ pushw %ax pushw %ds pushw %cs movzbw %cs:(size-_prefix), %ax shlw $9, %ax /* 512-byte blocks */ pushw %ax /* Relocate to free base memory, switch stacks */ pushw $12 /* Preserve exit code & far ret addr */ call prelocate /* We are now running in RAM */ popw %ax /* padding */ movw %cs, %ax movw %ax, %ds popw %ds:(_prefix_rom+2) /* ROM size */ popw %ds:(_prefix_rom+0) /* ROM segment */ popw %ds /* Original %ds */ popw %ax /* Original %ax */ pushw %ax /* 4-byte alignment */ pushl $8 /* Preserve exit code & far ret addr */ pushw $0 /* Set null return address */ jmp _start .section ".text16", "ax", @progbits .globl prefix_exit prefix_exit: popw %ax /* padding */ popw %ax /* %ax = exit code */ cmpw $EXIT_VIA_LRET, %ax jne 1f /* Exit via LRET */ lret 1: addw $4, %sp /* Strip padding */ cmpw $EXIT_VIA_BOOT_INT, %ax jne 2f /* Exit via int BOOT_INT */ int $BOOT_INT /* Try original vector */ 2: /* Exit via int $0x18 */ int $0x18 /* As per BIOS Boot Spec, next dev */ .globl prefix_exit_end prefix_exit_end: .previous /* UNDI loader needs to be rewritten to use new mechanism */ #if 0 #ifdef PXE_EXPORT #define PXENV_UNDI_LOADER 0x104d .section ".prefix" UNDILoader: /* Loader API is different to the usual PXE API; there is no * opcode on the stack. We arrange the stack to look like a * normal PXE API call; this makes the Etherboot internals * cleaner and avoids adding an extra API type just for the * PXE loader. */ pushw %bx movw %sp, %ax /* Store original %ss:sp */ pushw %ss pushw %ax pushl %eax /* Space for loader structure ptr */ pushw %bp movw %sp, %bp movw 16(%bp), %ax /* Copy loader structure ptr */ movw %ax, 2(%bp) movw 18(%bp), %ax movw %ax, 4(%bp) popw %bp pushw $PXENV_UNDI_LOADER /* PXE 'opcode' */ pushl %eax /* dummy return address */ /* Stack now looks like a normal PXE API call */ /* Store ROM segment and size on stack */ pushw %ax pushw %cs movzbw %cs:(size-_prefix), %ax shlw $9, %ax /* 512-byte blocks */ pushw %ax /* Unpack Etherboot into temporarily claimed base memory */ pushw $20 /* Dummy ret, PXE params, orig ss:sp */ call prelocate popw %ax /* discard */ popw %cs:(_prefix_rom+2) /* ROM size */ popw %cs:(_prefix_rom+0) /* ROM segment */ popw %ax /* Original %ax */ /* Inhibit automatic deallocation of base memory */ movl $0, %cs:_prefix_image_basemem /* Make PXE API call to Etherboot */ pushl $0x201 /* PXE API version */ /* Need to USE_INTERNAL_STACK, since we will call relocate() */ pushl $(EB_OPCODE_PXE|EB_USE_INTERNAL_STACK) /* PXE API call type */ call _entry addw $18, %sp /* discard */ popw %bx /* Restore original %ss:sp */ popw %ss movw %bx, %sp popw %bx call deprelocate lret $2 /* Skip our PXE 'opcode' */ #endif /* PXE_EXPORT */ #endif /* 0 */ #ifdef DEBUG_ROMPREFIX .section ".prefix" print_bcv: pushw %si movw $1f-_prefix, %si call print_message popw %si ret 1: .asciz "ROM detected\r\n" print_bev: pushw %si movw $1f-_prefix, %si call print_message popw %si ret 1: .asciz "booting\r\n" print_notpnp: pushw %si movw $1f-_prefix, %si call print_message popw %si ret 1: .asciz ": Non-PnP BIOS detected!\r\n" print_legacyentry: pushw %si movw $1f-_prefix, %si call print_message popw %si ret 1: .asciz "ROM using legacy boot mechanism\r\n" print_installed: pushw %si movw $1f-_prefix, %si call print_message popw %si ret 1: .ascii "hooked boot via INT" #ifdef BOOT_INT18H .asciz "18\r\n" #else .asciz "19\r\n" #endif print_start_int: pushw %si movw $1f-_prefix, %si call print_message popw %si ret 1: .asciz "booting via hooked interrupt\r\n" print_message: pushaw pushw %ds pushw %cs popw %ds pushw %si movw $1f-_prefix, %si call print_string popw %si call print_string popw %ds popaw ret 1: .asciz "Etherboot " print_string: 1: lodsb testb %al,%al je 2f movw $0x0007, %bx /* page 0, attribute 7 (normal) */ movb $0x0e, %ah /* write char, tty mode */ int $0x10 jmp 1b 2: ret #endif