/**
* Get the PXE entry point address.
*
* @return Whether the entry point could be found.
*/
static bool get_entry_point(void) {
bios_regs_t regs;
pxenv_t *pxenv;
pxe_t *pxe;
/* Use the PXE installation check function. */
bios_regs_init(®s);
regs.eax = INT1A_PXE_INSTALL_CHECK;
bios_call(0x1a, ®s);
if (regs.eax != INT1A_PXE_INSTALL_CHECK_RET || regs.eflags & X86_FLAGS_CF) {
dprintf("pxe: loaded via PXE but PXE not available\n");
return false;
}
/* Get the PXENV+ structure. */
pxenv = (pxenv_t *)segoff_to_linear((regs.es << 16) | regs.bx);
if (memcmp(pxenv->signature, PXENV_SIGNATURE, sizeof(pxenv->signature)) != 0) {
boot_error("PXENV+ structure has incorrect signature");
} else if (!checksum_range(pxenv, pxenv->length)) {
boot_error("PXENV+ structure is corrupt");
}
/* Get the !PXE structure. */
pxe = (pxe_t *)segoff_to_linear(pxenv->pxe_ptr);
if (memcmp(pxe->signature, PXE_SIGNATURE, sizeof(pxe->signature)) != 0) {
boot_error("!PXE structure has incorrect signature");
} else if (!checksum_range(pxe, pxe->length)) {
boot_error("!PXE structure is corrupt");
}
pxe_entry_point = pxe->entry_point_16;
return true;
}
static const struct acpi_rsdp *scan_for_rsdp(uint32_t base, uint32_t end)
{
for (base &= ~15; base < end-20; base += 16) {
const struct acpi_rsdp *rsdp = (const struct acpi_rsdp *)base;
if (memcmp(rsdp->magic, "RSD PTR ", 8))
continue;
if (checksum_range(rsdp, 20))
continue;
if (rsdp->rev > 0) {
if (base + rsdp->len >= end ||
checksum_range(rsdp, rsdp->len))
continue;
}
return rsdp;
}
return NULL;
}
static enum tbl_errs is_valid_table(const void *ptr)
{
const struct acpi_hdr *hdr = ptr;
if (hdr->sig[0] == 0)
return ERR_NOSIG;
if (hdr->len < 10 || hdr->len > (1 << 20)) {
/* Either insane or too large to dump */
return ERR_SIZE;
}
return checksum_range(hdr, hdr->len) == 0 ? ERR_NONE : ERR_CSUM;
}
