diff options
Diffstat (limited to 'src/arch/i386/prefix/romprefix.S')
| -rw-r--r-- | src/arch/i386/prefix/romprefix.S | 278 |
1 files changed, 215 insertions, 63 deletions
diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S index 167641c6e..d37cce94d 100644 --- a/src/arch/i386/prefix/romprefix.S +++ b/src/arch/i386/prefix/romprefix.S @@ -6,6 +6,11 @@ * table so using a noticeable amount of stack space is a no-no. */ +#define PNP_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'n' << 16 ) + ( 'P' << 24 ) ) +#define PMM_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'M' << 16 ) + ( 'M' << 24 ) ) +#define STACK_MAGIC ( 'L' + ( 'R' << 8 ) + ( 'E' << 16 ) + ( 'T' << 24 ) ) +#define PNP_GET_BBS_VERSION 0x60 + .text .code16 .arch i386 @@ -15,7 +20,9 @@ romheader: .word 0xAA55 /* BIOS extension signature */ romheader_size: .byte _load_size_sect /* Size in 512-byte blocks */ - jmp init_vector /* Initialisation vector */ + jmp init /* Initialisation vector */ +checksum: + .byte 0 .org 0x16 .word undiheader .org 0x18 @@ -72,7 +79,7 @@ pnpheader: .byte 0x54 /* Device indicator */ .word 0x0000 /* Boot connection vector */ .word 0x0000 /* Disconnect vector */ - .word exec_vector /* Boot execution vector */ + .word bev_entry /* Boot execution vector */ .word 0x0000 /* Reserved */ .word 0x0000 /* Static resource information vector*/ .equ pnpheader_len, . - pnpheader @@ -98,60 +105,210 @@ undiheader: .equ undiheader_len, . - undiheader .size undiheader, . - undiheader -/* Initialisation vector +/* Initialisation (called once during POST) * * Determine whether or not this is a PnP system via a signature * check. If it is PnP, return to the PnP BIOS indicating that we are * a boot-capable device; the BIOS will call our boot execution vector * if it wants to boot us. If it is not PnP, hook INT 19. */ -init_vector: - pushw %si - cmpw $'$'+'P'*256, %es:0(%di) - jne notpnp - cmpw $'n'+'P'*256, %es:2(%di) - jne notpnp -ispnp: - movw $ispnp_message, %si - jmp 99f -notpnp: +init: + /* Preserve registers, clear direction flag, set %ds=%cs */ + pushaw pushw %ds - pushw $0 - popw %ds + pushw %es + cld pushw %cs - pushw $exec_vector - popl ( 0x19 * 4 ) popw %ds - movw $notpnp_message, %si -99: + /* Print message as early as possible */ + movw $init_message, %si + call print_message + /* Check for PnP BIOS */ + testw $0x0f, %di /* PnP signature must be aligned - bochs */ + jnz hook_int19 /* uses unalignment to indicate 'fake' PnP. */ + cmpl $PNP_SIGNATURE, %es:0(%di) + jne hook_int19 + /* Is PnP: print PnP message */ + movw $init_message_pnp, %si + call print_message + xchgw %bx, %bx + /* Check for BBS */ + pushw %es:0x1b(%di) /* Real-mode data segment */ + pushw %ds /* &(bbs_version) */ + pushw $bbs_version + pushw $PNP_GET_BBS_VERSION + lcall *%es:0xd(%di) + addw $8, %sp + testw %ax, %ax + jne hook_int19 + movw $init_message_bbs, %si + call print_message + jmp hook_bbs + /* Not BBS-compliant - must hook INT 19 */ +hook_int19: + movw $init_message_int19, %si + call print_message + xorw %ax, %ax + movw %ax, %es + pushw %cs + pushw $int19_entry + popl %es:( 0x19 * 4 ) +hook_bbs: + /* Check for PMM */ + movw $( 0xe000 - 1 ), %di +pmm_scan: + incw %di + jz no_pmm + movw %di, %es + cmpl $PMM_SIGNATURE, %es:0 + jne pmm_scan + xorw %bx, %bx + xorw %si, %si + movzbw %es:5, %cx +1: es lodsb + addb %al, %bl + loop 1b + jnz pmm_scan + /* PMM found: print PMM message */ + movw $init_message_pmm, %si call print_message + /* Try to allocate 2MB block via PMM */ + pushw $0x0006 /* Aligned, extended memory */ + pushl $0xffffffff /* No handle */ + pushl $( 0x00200000 / 16 ) /* 2MB in paragraphs */ + pushw $0x0000 /* pmmAllocate */ + lcall *%es:7 + addw $12, %sp + testw %dx, %dx /* %ax==0 even on success, since align=2MB */ + jnz gotpmm + movw $init_message_pmm_failed, %si + call print_message + jmp no_pmm +gotpmm: /* PMM allocation succeeded: copy ROM to PMM block */ + pushal /* PMM presence implies 1kB stack */ + movw %ax, %es /* %ax=0 already - see above */ + pushw %dx + pushw %ax + popl %edi + movl %edi, image_source + xorl %esi, %esi + movzbl romheader_size, %ecx + shll $9, %ecx + addr32 rep movsb /* PMM presence implies flat real mode */ + movl %edi, decompress_to + /* Shrink ROM and update checksum */ + xorw %bx, %bx + xorw %si, %si + movw $_prefix_size_sect, %cx + movb %cl, romheader_size + shlw $9, %cx +1: lodsb + addb %al, %bl + loop 1b + subb %bl, checksum + popal +no_pmm: + /* Print CRLF to terminate messages */ + movw $'\n', %ax + call print_character + /* Restore registers */ + popw %es + popw %ds + popaw + /* Indicate boot capability to PnP BIOS, if present */ movw $0x20, %ax - popw %si lret - .size init_vector, . - init_vector - -ispnp_message: - .asciz "gPXE detected PnP BIOS\r\n" - .size ispnp_message, . - ispnp_message -notpnp_message: - .asciz "gPXE detected non-PnP BIOS\r\n" - .size notpnp_message, . - notpnp_message - -/* Boot execution vector - *pciheader_size - * Called by the PnP BIOS when it wants to boot us, or via the hooked - * INT 19 if we detected a non-PnP BIOS. - */ -exec_vector: - /* Obtain a reasonably-sized stack */ + .size init, . - init + +init_message: + .asciz "gPXE (http://etherboot.org) -" + .size init_message, . - init_message +init_message_pnp: + .asciz " PnP" + .size init_message_pnp, . - init_message_pnp +init_message_bbs: + .asciz " BBS" + .size init_message_bbs, . - init_message_bbs +init_message_pmm: + .asciz " PMM" + .size init_message_pmm, . - init_message_pmm +init_message_pmm_failed: + .asciz "(failed)" + .size init_message_pmm_failed, . - init_message_pmm_failed +init_message_int19: + .asciz " INT19" + .size init_message_int19, . - init_message_int19 + +/* ROM image location + * + * May be either within option ROM space, or within PMM-allocated block. + */ +image_source: + .long 0 + .size image_source, . - image_source + +/* Temporary decompression area + * + * May be either at HIGHMEM_LOADPOINT, or within PMM-allocated block. + */ +decompress_to: + .long HIGHMEM_LOADPOINT + .size decompress_to, . - decompress_to + +/* BBS version + * + * Filled in by BBS BIOS. We ignore the value. + */ +bbs_version: + .word 0 + +/* Boot Execution Vector entry point + * + * Called by the PnP BIOS when it wants to boot us. + */ +bev_entry: + pushw %cs + call exec + lret + .size bev_entry, . - bev_entry + +/* INT19 entry point + * + * Called via the hooked INT 19 if we detected a non-PnP BIOS. + */ +int19_entry: + pushw %cs + call exec + /* No real way to return from INT19 */ + int $0x18 + .size int19_entry, . - int19_entry + +/* Execute as a boot device + * + */ +exec: /* Set %ds = %cs */ + pushw %cs + popw %ds + + /* Print message as soon as possible */ + movw $exec_message, %si + call print_message + + /* Store magic word on BIOS stack and remember BIOS %ss:sp */ + pushl $STACK_MAGIC + movw %ss, %dx + movw %sp, %bp + + /* Obtain a reasonably-sized temporary stack */ xorw %ax, %ax movw %ax, %ss movw $0x7c00, %sp - - movw $exec_message, %si - call print_message - call install + /* Install gPXE */ + movl image_source, %esi + movl decompress_to, %edi + call alloc_basemem + call install_prealloc /* Set up real-mode stack */ movw %bx, %ss @@ -162,18 +319,28 @@ exec_vector: pushw $1f lret .section ".text16", "awx", @progbits -1: +1: /* Call main() */ pushl $main pushw %cs call prot_call - popl %eax /* discard */ + /* No need to clean up stack; we are about to reload %ss:sp */ + + /* Restore BIOS stack */ + movw %dx, %ss + movw %bp, %sp - /* Boot next device */ + /* Check magic word on BIOS stack */ + popl %eax + cmpl $STACK_MAGIC, %eax + jne 1f + /* BIOS stack OK: return to caller */ + lret +1: /* BIOS stack corrupt: use INT 18 */ int $0x18 .previous exec_message: - .asciz "gPXE starting boot\r\n" + .asciz "gPXE starting boot\n" .size exec_message, . - exec_message /* UNDI loader @@ -182,6 +349,7 @@ exec_message: */ undiloader: /* Save registers */ + pushl %esi pushl %edi pushw %es pushw %bx @@ -193,6 +361,8 @@ undiloader: pushw %di movw %es:12(%di), %bx movw %es:14(%di), %ax + movl %cs:image_source, %esi + movl %cs:decompress_to, %edi call install_prealloc popw %di /* Call UNDI loader C code */ @@ -208,24 +378,6 @@ undiloader: popw %bx popw %es popl %edi + popl %esi lret .size undiloader, . - undiloader - -/* Utility function: print string - */ -print_message: - pushw %ax - pushw %bx - pushw %bp - movw $0x0007, %bx -1: cs lodsb - testb %al, %al - je 2f - movb $0x0e, %ah /* write char, tty mode */ - int $0x10 - jmp 1b -2: popw %bp - popw %bx - popw %ax - ret - .size print_message, . - print_message |