Found some document about size determination in pci devices
had run lspi
jean@jean-Soisy:~$ sudo lspci -vv -k -xxxx -s 03:09.0
03:09.0 VGA compatible controller: NVIDIA Corporation NV44A [GeForce 6200] (rev
a1) (prog-if 00 [VGA controller])
Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR+ FastB2B- DisINTx-
Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 40 (1250ns min, 250ns max)
Interrupt: pin A routed to IRQ 21
Region 0: Memory at 94000000 (32-bit, non-prefetchable) [size=16M]
Region 1: Memory at c0000000 (32-bit, prefetchable) [size=512M]
Region 2: Memory at 92000000 (32-bit, non-prefetchable) [size=16M]
[virtual] Expansion ROM at e0000000 [disabled] [size=128K]
Capabilities: [60] Power Management version 2
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Kernel driver in use: nouveau
00: de 10 21 02 06 01 b0 02 a1 00 00 03 00 28 00 00
10: 00 00 00 94 08 00 00 c0 00 00 00 92 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
30: 00 00 00 00 60 00 00 00 00 00 00 00 09 01 05 01
40: 00 00 00 00 02 00 30 00 03 00 00 1f 00 00 00 00
50: 00 00 00 00 01 00 00 00 ce d6 23 00 0f 00 00 00
60: 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90: 00 00 00 00 00 00 00 00 01 04 40 c1 00 00 00 00
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
So, value defines as BAR1 located at adress 0x14 in parameters with
value 08 00 00 c0
means : adress is 0xc0000000 with 0x8 = prefetchable
for memory size determination methos is
https://wiki.osdev.org/PCI
https://stackoverflow.com/questions/19006632/how-is-a-pci-pcie-bar-size-determined/39618552#39618552
To determine the amount of address space needed by a PCI device, you must save
the original value of the BAR,
write a value of all 1's to the register, then read it back.
The amount of memory can then be determined by masking the information bits,
performing a bitwise NOT ('~' in C), and incrementing the value by 1. The
original value of the BAR should then be restored.
on my computer : using sudo bless
parameter are located at /sys/bus/pci/devices/0000:03:09.0/config
replaced 08 00 00 c0 by ff ff ff ff then, computer blocked, but was able to
read 08 00 00 e0
that means
dropping 4 bits LSB -> 00 00 00 e0
inverting bitwise ff ff ff 10
adding one 00 00 00 20 means 512 M
BUT https://www.xilinx.com/Attachment/PCI_SPEV_V3_0.pdf
6.2.5.1. Address Maps
Devices are free to consume more address space than required
after explanation of a computation method, precision is given
The resultant 32-bit value is the memory/I/O range size decoded by the
register.
I Think that the problem is here = adress space decoded, but not
populated
Regards
Jean COLIN
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https://bugs.launchpad.net/bugs/1737423
Title:
With a (cheap) video card in PCI Geforce 6200 (NV44A) with 256Mb video
memory misdetected as 512 Mb : result was kernel panic in worst case
and memory crash in best case
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