Entrance point (ipl and linuxbios)

[Xavier Pegenaute]

Hi,

i have some doubt about the real entrance point in the eeprom and ipl 
with LinuxBios.

if the map of eeprom is right (following burn_mtd sript):

0-511 (0x0 - 0x1FF) docipl 512 Bytes
512-1023 (0x200 - 0x3FF)  docipl (security copy) 512 Bytes
1024-65535 (0x400 - 0xFFFF)  linuxbios.block 64512 Bytes
65536-851967 (0x10000 - 0xCFFFF)  vmlinux.bin.gz.block 786432 Bytes

In theory we have mapped the completly EPROM into the top of memory (4Gb 
for 32 bits) (Vol. 3 Cap. 9.10 of IA-32 ...), how we have the CS.BASE = 
0xFFFF0000 and EIP = 0x0000FFF0 with the special memory config we start 
in 0xFFFFFFF0. We only can see a range of 0x0000 - 0xFFFF (the last 
64Kbytes?) until we turn to protected mode.
Then we start the init of EPROM with the last 16 bytes below the top of 
memory, that is the last 16 bytes below of vmlinux.bin.gz, of course 
impossible, any one can help me in this ?

Also, in ipl.S, we can find this code:

-----------------------------------------------------------------------
#ifdef STD_FLASH
    .org 0xfff0
reset_vector:
    .byte    0xea                # jmp to f000:fc00, where IPL
    .word    0xfc00, 0xf000            # starts in Standard Flash
#else /* !STD_FLASH i.e. DoC Mil */
-----------------------------------------------------------------------
Here if we have a standard flash eeprom we jump to the code of 
initialitzacion "sis630spd_start:" in ipl.S and we execute until 
"sis630ipl_end:" that there is a
jump to SPL vector.
What about ".org 0xfff0" ?
-----------------------------------------------------------------------
#if (USE_DOC_MIL == 1)
    .org 0x1f0
-----------------------------------------------------------------------
If we have DOC_MIL ".org 0x1f0".
-----------------------------------------------------------------------
#elif USE_DOC_2000_TSOP == 1) || (USE_DOC_MIL_PLUS == 1)
    .org 0x3f0
-----------------------------------------------------------------------
and here we put the ".org 0x3f0"
-----------------------------------------------------------------------
#endif
reset_vector:
    .byte    0xea                # jmp to fe00:0000, where IPL
    .word    0x0000, DOC_WIN_SEG        # starts in DoC
#endif /* STD_FLASH */
-----------------------------------------------------------------------
If it is not a DOC_MIL and bla, bla, bla ... we make a jmp to 
0xfe00:000, what is there in this direction ?
-----------------------------------------------------------------------
spl_vector:
    .byte    0xea                # jmp to 8000:0000, where SPL
    .word    0x0000, SPL_RAM_SEG        # (LinuxBIOS) starts in RAM
-----------------------------------------------------------------------
And finally if it was a standard flash or DOC_MIL we jump to LinuxBios 
in the segment 0x8000. In theory LinuxBios ?.

My questions:
- May be the mapped EEPROM in memory address space is mapped in reverse 
order (to find linuxbios in the firs 64Kb) ? 0x0 of EEPROM -> 0xFFFFFFFF.
- Who is executed first ipl.S, or crt0.S ?
My confusion are the ".org 0xfff0" in ipl.S but in the same time in 
src/cpu/i386/reset["16","32"].inc i found some reference to reset_vector 
but i don't know how it works , also by the other hand who turn the 
memory in protected memory is crt0.S, then this has to be the first.


Thanks by patience.
Sorry by the extension of the mail.
Xavi.