Hello all,
I want to create a program that runs from a
pxe-loaded virtual floppy (using memdisk + keeppxe) to
call again PXE boot.
I took a piece of code form NILO to look for PXE
data structures and the call to function
PXENV_START_BASE from PXE spec as follows:
lower = (unsigned char *)LOWER_PXE_MEM;
upper = (unsigned char *)UPPER_PXE_MEM;
for (i=upper; i>lower;i--) {
if (memcmp (i, sig, size) == 0) {
/* We found it. Now see if it's usable. */
/* Look for the version number. As the
names of this field
are different for the PXE and PXENV
structures, we use an
offset of 6 bytes, which is the same
for both structures. */
if (*(i+6) != rev) {
printf ("PXE version 0x%02x too
low.\r\n", *(i+6));
} else {
printf ("Found the %s data structure
at 0x%04x\r\n",
(type == PXE) ? "!PXE"
: "PXENV+", i);
return (i);
}
}
However, this function never finds the PXE signatures.
Does anybody has any suggestion to make it work? After
finding the structure, I need to call function to see
if it returns to PXE boot again:
pxe_data_struct->entry16point (PXENV_START_BASE ,
(void *)0)
where pxe_data_struct looks as follows:
typedef struct pxe_s {
u_int8_t signature[4]; /* Structure signature is
not NULL */
/* terminated. FIXME: this was 4 */
u_int8_t structlength; /* Length of this structure
in */
/* bytes. */
u_int8_t structcksum; /* Use to make byte checksum
of this */
/* structure == zero. */
u_int8_t structrev; /* Structure format revision
number. */
u_int8_t reserved1; /* must be zero */
undi_romid_t *undi; /* Far pointer to UNDI
ROMID */
bc_romid_t *base; /* Far pointer to
base-code ROMID */
u_int16_t (*entry16point)(u_int16_t func, void
*param);
/* 16bit stack segment
API entry */
/* point. This will be seg:off in */
/* real mode and sel:off in 16:16 */
/* protected mode. */
u_int16_t (*entry32point)(u_int16_t func, void
*param);
/* 32bit stack segment API entry */
/* point. This will be sel:off. */
/* In real mode, sel == 0 */
u_int16_t (*statuscallout)(u_int16_t param);
/* Address of DHCP/TFTP status */
/* callout routine. */
u_int8_t reserved2; /* must be zero */
u_int8_t segdesccnt; /* Number of segment
descriptors in */
/* this structure. */
u_int16_t firstselector; /* First segment
descriptor in GDT */
/* assigned to PXE. */
newsegdesc_t stack;
newsegdesc_t undidata;
newsegdesc_t undicode;
newsegdesc_t undicodewrite;
newsegdesc_t bc_data;
newsegdesc_t bc_code;
newsegdesc_t bc_codewrite;
} pxe_t;
Any ideas?
Thanks
/Oscar
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