diff options
Diffstat (limited to 'pxe.S')
| -rw-r--r-- | pxe.S | 117 |
1 files changed, 117 insertions, 0 deletions
@@ -0,0 +1,117 @@ +/* + * pxe.S Copyright (C) 2012 Michael Brown <mcb30@ipxe.org> + * + * pxe.S is loaded at 0x7c00 by the PXE ROM. It copies the 32-bit + * portion to 0x10000 and jumps into setup.S. + */ + +#include "defs.h" + +#define RMSIZE (0x200 + 0x200*SETUPSECS) + +#define PXENV_ENTRY 0x0a +#define PXENV_UNDI_SHUTDOWN 0x0005 +#define PXENV_FILE_CMDLINE 0x00e8 + +#define CMDLINE_MAGIC 0xa33f + +.code16 +.section ".bootsect", "ax", @progbits +.org 0 +_pxe: + +.globl _main +_main: + /* Canonicalise addresses */ + ljmp $BOOTSEG, $pxe_start + + /* Command line magic */ +.org 0x20 +cmdline_magic: + .word 0 +cmdline_offset: + .word 0 + +pxe_start: + /* Preserve registers, %ss:%esp, and magic marker on PXE stack */ + pushfl + pushal + pushw %gs + pushw %fs + pushw %es + pushw %ds + pushl %esp + pushw %ss + pushw %ax /* Padding */ + pushl $EXIT_MAGIC + + /* Store PXENV+ entry point */ + movl %es:PXENV_ENTRY(%bx), %eax + movl %eax, %cs:pxenv_vector + + /* Copy 32-bit portion to TSTLOAD:0000. Perform copy in + * reverse in 1kB blocks, since regions will overlap and we + * need to copy more than the 64kB real-mode segment limit. + */ + movw $_syssize, %bx /* Length is _syssize (paragraphs) */ + addw $63, %bx + andw $~63, %bx /* Round up to nearest kB */ + movw $(BOOTSEG + (RMSIZE >> 4)), %ax + addw %bx, %ax + movw %ax, %ds + movw $TSTLOAD, %ax + addw %bx, %ax + movw %ax, %es +1: movw %ds, %ax /* Decrement %ds and %es by 1kB */ + subw $64, %ax + movw %ax, %ds + movw %es, %ax + subw $64, %ax + movw %ax, %es + movw $256, %cx /* Copy 1kB block */ + xorw %si, %si + xorw %di, %di + cld + rep movsl + subw $64, %bx + jnz 1b + + /* Set up %ds and %es for access to local variables */ + movw %cs, %ax + movw %ax, %ds + movw %ax, %es + + /* Check for a command line */ + movw $PXENV_FILE_CMDLINE, %bx + movw $pxenv_file_cmdline, %di + lcall *pxenv_vector + testw %ax, %ax + jnz no_cmdline + movw pxenv_file_cmdline + 2, %ax + testw %ax, %ax + jz no_cmdline + movw $CMDLINE_MAGIC, cmdline_magic + movw $RMSIZE, cmdline_offset +no_cmdline: + + /* Shutdown NIC */ + movw $PXENV_UNDI_SHUTDOWN, %bx + movw $pxenv_undi_shutdown, %di + lcall *pxenv_vector + + /* Jump to setup.S */ + ljmp $(BOOTSEG + 0x20), $0 + +pxenv_vector: + .word 0,0 + +pxenv_undi_shutdown: + .word 0 /* Status */ + +pxenv_file_cmdline: + .word 0 /* Status */ + .word 0xffff /* 64kB max length of command line */ + .word RMSIZE, BOOTSEG + +.org 512 +_epxe: |