This depends on the graphics card. It still works for me with a Radeon chip, it has never worked for me with a Matrox.

Please provide the output of hwinfo --gfxcard, and I'll see if I can find a similar card here and reproduce it.

machine 1: 

22: PCI(AGP) 100.0: 0300 VGA compatible controller (VGA)        
  [Created at pci.300]
  UDI: /org/freedesktop/Hal/devices/pci_1002_4e54
  Unique ID: VCu0.Bl6sNg5xBX0
  Parent ID: vSkL.1o+Z33xgwU4
  SysFS ID: /devices/pci0000:00/0000:00:01.0/0000:01:00.0
  SysFS BusID: 0000:01:00.0
  Hardware Class: graphics card
  Model: "IBM RV350 NT"
  Vendor: pci 0x1002 "ATI Technologies Inc"
  Device: pci 0x4e54 "RV350 NT"
  SubVendor: pci 0x1014 "IBM"
  SubDevice: pci 0x054f 
  Revision: 0x80
  Driver: "radeonfb"
  Memory Range: 0xe0000000-0xe7ffffff (rw,prefetchable)
  I/O Ports: 0x3000-0x3fff (rw)
  Memory Range: 0xc0100000-0xc010ffff (rw,non-prefetchable)
  Memory Range: 0xc0120000-0xc013ffff (ro,prefetchable,disabled)
  IRQ: 11 (21711293 events)
  I/O Ports: 0x3c0-0x3df (rw)
  Module Alias: "pci:v00001002d00004E54sv00001014sd0000054Fbc03sc00i00"
  Driver Info #0:
    XFree86 v4 Server Module: radeon
    XF86Config Entry: Option "DynamicClocks" "on"
  Driver Info #1:
    XFree86 v4 Server Module: fglrx
    3D Support: yes
    Extensions: dri
  Config Status: cfg=yes, avail=yes, need=yes, active=unknown
  Attached to: #11 (PCI bridge)

Primary display adapter: #22

machine 2:

10: PCI 02.0: 0300 VGA compatible controller (VGA)
  [Created at pci.295]
  UDI: /org/freedesktop/Hal/devices/pci_8086_2592
  Unique ID: _Znp.AA0FlerDir8
  SysFS ID: /devices/pci0000:00/0000:00:02.0
  SysFS BusID: 0000:00:02.0
  Hardware Class: graphics card
  Model: "Samsung Electronics 915 GM"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x2592 "915 GM"
  SubVendor: pci 0x144d "Samsung Electronics Co Ltd"
  SubDevice: pci 0xc01a 
  Revision: 0x03
  Memory Range: 0xb0080000-0xb00fffff (rw,non-prefetchable)
  I/O Ports: 0x1800-0x1807 (rw)
  Memory Range: 0xc0000000-0xcfffffff (rw,prefetchable)
  Memory Range: 0xb0000000-0xb003ffff (rw,non-prefetchable)
  IRQ: 11 (no events)
  I/O Ports: 0x3c0-0x3df (rw)
  Module Alias: "pci:v00008086d00002592sv0000144Dsd0000C01Abc03sc00i00"
  Driver Info #0:
    XFree86 v4 Server Module: i810
  Driver Info #1:
    XFree86 v4 Server Module: i810
    3D Support: yes
    Extensions: dri
  Config Status: cfg=yes, avail=yes, need=yes, active=unknown

11: PCI 02.1: 0380 Display controller
  [Created at pci.295]
  UDI: /org/freedesktop/Hal/devices/pci_8086_2792
  Unique ID: ruGf.SzVewQ5Dr7B
  SysFS ID: /devices/pci0000:00/0000:00:02.1
  SysFS BusID: 0000:00:02.1
  Hardware Class: graphics card
  Model: "Samsung Electronics Mobile 915GM/GMS/910GML Express Graphics Controller"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x2792 "Mobile 915GM/GMS/910GML Express Graphics Controller"
  SubVendor: pci 0x144d "Samsung Electronics Co Ltd"
  SubDevice: pci 0xc01a 
  Revision: 0x03
  Memory Range: 0x53000000-0x5307ffff (rw,non-prefetchable,disabled)
  Module Alias: "pci:v00008086d00002792sv0000144Dsd0000C01Abc03sc80i00"
  Config Status: cfg=yes, avail=yes, need=yes, active=unknown

Primary display adapter: #10

I couldn't reproduce this. However these two graphics adapters are known to do DDC probes, so the availability of the videomode may depend on the attached monitor/cabling/KVM switch/...

Did the exact same hardware setup work for you with 10.0?

Could you please try with vga=0x311 ? This is 640x480 and should work regardless of whether DDC was successful or not.

0x311 works fine, and yes, it worked on one of the laptops before just fine..

these are laptops and I'm trying to set their native resolution on the console. what was the tool to probe ddc again?

Which of the two laptops worked before? The one with the Intel card or the one with the ATI? I think I'll have to compare the sources and see what has changed since 10.0

I think that DDC is done automatically by the card to restrict available video modes to those supported by the monitor. I am not aware of any tool in our distribution that does DDC probes. Of course it's integrated into X.

hmm, hwinfo --monitor can do DDC probes. it seems it advertises only 1400x1050, for which apparently no vesa mode number exists. bummer. 

strange thing is that this worked on the other laptop (which also reports correctly 1600x1200). I'll have to try it though, it currently panic'ed due to another kernel bug. 

I'm using vbetest to find out that 65k / 1400x1050 vesa mode is 0x14d, and i can set this mode from vbetool just fine. however, booting with vga=0x34d gives "unsupported video mode number"

Dirk, does this still happen on 10.3 or 11.0?
Which of the two laptop reports the wrong 1400x1050 resolution? The one with Intel or the one with Radeon?

the one with intel reports the wrong resolution. it still happens both with 10.3 and with 11.0. 

there is really little I can do without the hardware. I think we will need to bisect the kernel. It would be good to see if the framebuffer works with 
the vanilla 2.6.13 (which 10.0 is based on) and vanilla 2.6.16 (which 10.1 is based on)

So, if you have time, please test 2.6.13 (should work) and 2.6.16 (should not work). This should tell us whether the problem is caused by any of our patches.

I don't have time for this anymore. perhaps somewhen in the future.