multiple video card error

[truename]

There are four PCI video cards on the mainboard. They are the same with each other. I have 
written the driver myself running in XFree86 4.2.0. The four video cards work fine in Redhat 
7.0 when setting "xinerama" in the config file. 
Then I upgrade the driver in order to run in Xorg 1.6.4. The new driver can only make the 
primary video card work fine in Ubuntu 9.10(XServer version is 1.6.4) . But it cannot make 
four video cards work fine at the same time when setting "xinerama" in the config file. In 
the log I find that it can read rom of the primary video card. But it cannot read roms of 
the other video cards. The Xserver reports an error:
Cannot read V_BIOS (3) Input/output error
 
 I do some further work.
 
First I type the command "lspci -nv" and find the four video cards in pci address 03:01.0, 
03:02.0, 03:03.0 and 03:04.0.
    In "sys/bus/pci/devices/", there are four directories "0000:03:01.0\", "0000:03:02.0\", 
"0000:03:03.0\", "0000:03:04.0\". And there is a file named rom in each of the four 
directories.
    In Xserver's log file, I find that information about video bios of the four video cards 
are as follows.
    Primary V_BIOS segment is: 0xc000   (the primary card)
    Cannot read V_BIOS (3) Input/output error (the other cards)
    Then I tracked into source code of XServer and libpciaccess. In function 
xf86ExtendedInitInt10 in hw\xfree86\int10\generic.c, function pci_device_read_rom is called.
Function pci_device_read_rom calls function pci_device_linux_sysfs_read_rom in libpciaccess
-0.10.6\src\linux_sysfs.c. In function pci_device_linux_sysfs_read_rom, it read file 
"0000:03:0x.0\rom". This is where the error occurs. An error returns when reading 
"0000:03:02.0\rom" or "0000:03:03.0\rom" or "0000:03:04.0\rom". I wonder why it failed when 
reading "0000:03:02.0\rom" or "0000:03:03.0\rom" or "0000:03:04.0\rom" while it succedded 
when reading "0000:03:01.0\rom"?
  I believe each video bios is needed to be called to initialise each video card. But video 
bios of the 2nd, 3rd and 4th video card haven't been called successfully.
Any comments on this question would be appreciated. 
   Harry
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