I had got mini PC eBox-4854 made by DMP Electronics Inc. ( http://www.compactpc.com.tw/ebox-4854.htm ) and found onboard NIC (Realtek 8100B) and mini-PCI Wi-Fi module didn't work with errors:
rl0: watchdog timeout
and
ath0: ath_chan_set: unable to reset channel ...
Booting FreeBSD on another eBox-4854, playing with BIOS and sysctl settings, switching  ACPI/APIC and compiling custom kernels didn't help.
OpenBSD 4.3 experienced the same problems.
But in Linux (fc7) both devices worked OK.
This box uses VIA CX700M chipset, so I grep-ped linux kernel sources and found interesting piece of code:

/*
 * Disable PCI Bus Parking and PCI Master read caching on CX700
 * which causes unspecified timing errors with a VT6212L on the PCI
 * bus leading to USB2.0 packet loss. The defaults are that these
 * features are turned off but some BIOSes turn them on.
 */

uint8_t b;
if (pci_read_config_byte(dev, 0x76, &b) == 0) {
  if (b & 0x40) {
    /* Turn off PCI Bus Parking */
    pci_write_config_byte(dev, 0x76, b ^ 0x40);

    dev_info(&dev->dev,
      "Disabling VIA CX700 PCI parking\n");
   }
}

if (pci_read_config_byte(dev, 0x72, &b) == 0) {
  if (b != 0) {
    /* Turn off PCI Master read caching */
    pci_write_config_byte(dev, 0x72, 0x0);

    /* Set PCI Master Bus time-out to "1x16 PCLK" */
    pci_write_config_byte(dev, 0x75, 0x1);

    /* Disable "Read FIFO Timer" */
    pci_write_config_byte(dev, 0x77, 0x0);

    dev_info(&dev->dev,
      "Disabling VIA CX700 PCI caching\n");
  }
}

Here dev is
    vendor = 0x1106 'VIA Technologies Inc'
    device = 0x324e 'CX700 Internal Module Bus'
    class  = 0x060000 'HOST-PCI bridge'

Being done on FreeBSD, these steps fix the problem till the next system boot.

Fix: I think BIOS developers but not OS developers must fix this problem. But as long as not all of them do it, it will be good to include this quirk in FreeBSD's kernel code. Anyway, there is my script /usr/local/etc/rc.d/cx700fix in the attach.

Patch attached with submission follows:
How-To-Repeat: Boot FreeBSD on PC, based on VIA CX700* chipset. If BIOS doesn't initialize chipset correctly, like in my case, problem with some PCI devices using DMA transfer should appear.