Why some devices cannot be detected?

[Andrey V. Elsukov]

Hi, All.

I don't have this problem, but i saw it in several users reports.
System can't detect some devices. Last example (from one report):
Windows/Linux detected LSI MegaRAID SAS 8408E RAID Controller on
an motherboard, but freebsd didn't detect.

pciconf list:
hostb0 at pci0:0:0:0:   class=0x060000 card=0x83361033 chip=0x25d88086 
rev=0xb1 hdr=0x00
pcib1 at pci0:0:2:0:   class=0x060400 card=0x00000000 chip=0x25f78086 
rev=0xb1 hdr=0x01
pcib8 at pci0:0:3:0:   class=0x060400 card=0x00000000 chip=0x25e38086 
rev=0xb1 hdr=0x01
pcib9 at pci0:0:4:0:   class=0x060400 card=0x00000000 chip=0x25f88086 
rev=0xb1 hdr=0x01
pcib10 at pci0:0:5:0:   class=0x060400 card=0x00000000 chip=0x25e58086 
rev=0xb1 hdr=0x01
pcib11 at pci0:0:6:0:   class=0x060400 card=0x00000000 chip=0x25e68086 
rev=0xb1 hdr=0x01
pcib12 at pci0:0:7:0:   class=0x060400 card=0x00000000 chip=0x25e78086 
rev=0xb1 hdr=0x01
hostb1 at pci0:0:16:0:   class=0x060000 card=0x83361033 chip=0x25f08086 
rev=0xb1 hdr=0x00
hostb2 at pci0:0:16:1:   class=0x060000 card=0x83361033 chip=0x25f08086 
rev=0xb1 hdr=0x00
hostb3 at pci0:0:16:2:   class=0x060000 card=0x83361033 chip=0x25f08086 
rev=0xb1 hdr=0x00
hostb4 at pci0:0:17:0:   class=0x060000 card=0x83361033 chip=0x25f18086 
rev=0xb1 hdr=0x00
hostb5 at pci0:0:19:0:   class=0x060000 card=0x83361033 chip=0x25f38086 
rev=0xb1 hdr=0x00
hostb6 at pci0:0:21:0:   class=0x060000 card=0x83361033 chip=0x25f58086 
rev=0xb1 hdr=0x00
hostb7 at pci0:0:22:0:   class=0x060000 card=0x83361033 chip=0x25f68086 
rev=0xb1 hdr=0x00
pcib13 at pci0:0:28:0:   class=0x060400 card=0x83361033 chip=0x26908086 
rev=0x09 hdr=0x01
uhci0 at pci0:0:29:0:   class=0x0c0300 card=0x83361033 chip=0x26888086 
rev=0x09 hdr=0x00
uhci1 at pci0:0:29:1:   class=0x0c0300 card=0x83361033 chip=0x26898086 
rev=0x09 hdr=0x00
uhci2 at pci0:0:29:2:   class=0x0c0300 card=0x83361033 chip=0x268a8086 
rev=0x09 hdr=0x00
uhci3 at pci0:0:29:3:   class=0x0c0300 card=0x83361033 chip=0x268b8086 
rev=0x09 hdr=0x00
ehci0 at pci0:0:29:7:   class=0x0c0320 card=0x83361033 chip=0x268c8086 
rev=0x09 hdr=0x00
pcib14 at pci0:0:30:0:   class=0x060401 card=0x83361033 chip=0x244e8086 
rev=0xd9 hdr=0x01
isab0 at pci0:0:31:0:   class=0x060100 card=0x83361033 chip=0x26708086 
rev=0x09 hdr=0x00
atapci0 at pci0:0:31:1:   class=0x01018a card=0x83361033 chip=0x269e8086 
rev=0x09 hdr=0x00
none0 at pci0:0:31:3:   class=0x0c0500 card=0x83361033 chip=0x269b8086 
rev=0x09 hdr=0x00
pcib2 at pci0:1:0:0:   class=0x060400 card=0x83361033 chip=0x35008086 
rev=0x01 hdr=0x01
pcib7 at pci0:1:0:3:   class=0x060400 card=0x83361033 chip=0x350c8086 
rev=0x01 hdr=0x01
pcib3 at pci0:2:0:0:   class=0x060400 card=0x83361033 chip=0x35108086 
rev=0x01 hdr=0x01
pcib6 at pci0:2:2:0:   class=0x060400 card=0x83361033 chip=0x35188086 
rev=0x01 hdr=0x01
pcib4 at pci0:3:0:0:   class=0x060400 card=0x00000000 chip=0x03708086 
rev=0x00 hdr=0x01
pcib5 at pci0:3:0:2:   class=0x060400 card=0x00000000 chip=0x03728086 
rev=0x00 hdr=0x01
em0 at pci0:12:0:0:   class=0x020000 card=0x83361033 chip=0x10968086 
rev=0x01 hdr=0x00
em1 at pci0:12:0:1:   class=0x020000 card=0x83361033 chip=0x10968086 
rev=0x01 hdr=0x00
mpt0 at pci0:13:5:0:   class=0x010000 card=0x83361033 chip=0x00541000 
rev=0x01 hdr=0x00
vgapci0 at pci0:36:0:0:   class=0x030000 card=0x83361033 chip=0x0522102b 
rev=0x02 hdr=0x00

Windows detects it as

Device Description   LSI MegaRAID SAS 8408E RAID Controller
Bus Type   PCI-X
Bus / Device / Function   4 / 14 / 0
Device ID   1000-0411
Subsystem ID   1000-1001
Device Class   0104 (RAID Controller)
Revision   00
Fast Back-to-Back Transactions   Not Supported

Device Features
66 MHz Operation   Supported
Bus Mastering   Enabled

PCI-X Device Properties
64-bit Device   Yes
133 MHz Operation   Supported
PCI-X 266   Not Supported
PCI-X 533   Not Supported
---------------------------------------

So, question is why freebsd can't detect this device?

-- 
WBR, Andrey V. Elsukov