[coreboot] Status of Intel Poulsbo US15W

Sebastian Andrzej Siewior sebastian at breakpoint.cc
Fri Oct 12 12:40:42 CEST 2012

Does anyone have an idea what the status of Intel's poulsbou in current
coreboot is?
- cmc contained no mem config. So I dumped the registers from the running
  system (sch, port1, reg0..2) from the running system and filled out
  sysinfo->ranks, cl, trcd, trp, device_density, data_width based on those
- I noticed that my FSB runs at 533MHz. So I set the lower bit in
  SCH_MSG_DUNIT_REG_DCO (the orignial code sets BIT 0 if FSB is 533 but then
  throwes it away and writes 0x006911c).

- The SCH register 2, 8 is set to 0x40000000 (1GiB). The original
  BIOS sets this to 0x80000000 (2GiB) which would also match the magic with
  data_width, ranks & device_density which result is overwritten. Is this
  correct? What is the purpose of this value?

- In sch_shadow_CMC(). I have no idea why cpuid_eax(0x80000008) should be
  written in that register. I haven't found any documentation claiming that
  it should be done.
  The system hangs after executing a wbinvd like the manual says. That is
  probably why the cmc code is copied twice and the wbinvd is commented out.
  It hangs mostlikely due to the CAR setup. So maybe it could be moved to
  southbridge setup somewhere.

- in src/northbridge/intel/sch/northbridge.c, pci_domain_set_resources() is
  using PCI device (0,0) register 0x9c is used to figure out how much memory
  is available. I read 0x0 here in original bios and coreboot. I assigned 1
  GiB here for the variable. Is this a BIOS set variable?
  This file / function looks like a copy of src/northbridge/intel/i945/northbridge.c.
  For TOM it could be SCH (2, 8) because this is written by sdram_initialize()
  (with the wrong value in my setup however). It is just a guess however.
  The next part reads GGC register and I belive from wrong device as it should
  be PCI_DEVFN(2, 0). Atlteast it is written in iWRainbowG6's romstage.c
  TSEG is read from pci dev (0,0) register 0x9e. I'm not sure this is correct,
  I don't see any place that this is written.

- I extraced the VGA ROM from the BIOS. After attaching it I see three
  unhandled INT15 calls with AX=0x5f35, AX=0x5f40, AX=0x5f35. After that
  coreboot continues, display remains blank. Is it possible to emulate these
  calls to get some output? Linux somehow des not do anything right now…

- After booting I get errors from the ehci controller after attaching a
  highspeed device. Attaching a keyboard seems to works. Is there something
  I have to tweak to get highspeed USB working?

I could send patches for some of things but I am not always sure what I do


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