If you have no operating system installed on the host that you want to use for ESXi but you know the device vender and model, you can use a resource like http://pci-ids.ucw.cz/ or http://www.pcidatabase.com/ to find out what the PCI vender and device ID will be. You can then compare that with this list. If the storage and network controller are listed, then it is possible that you will be able to successfully install ESXi on the host you plan to use. It is of course best to use a system that is fully supported and that list can be found here.
Should you have an OS installed, you can uses system tools like lspci for Linux or device manager for Windows to find the PCI IDs. Do the following for Windows.
1) Right click on My Computer and select Manage.
2) In Computer Management, select Device Manager and bring up the properties for the device.
3) Select the Details tabs and the Hardware Ids property. In the below example, the Vender ID is 8086 (Intel) and the Device ID is 27c4 (ICH7 SATA Controller). In this case, simple.map has an entry for this device and ESXi will load ata_piix driver for the controller.
It is also possible to find this information by booting a system with the ESXi install CD. This process is shown below.
Finding a device’s PCI IDs using the ESXi boot CD
1) Boot your system with the ESXi install CD.
2) Once you have reached the install screen, press ALT-F1 to access the console for ESXi. Log in with the account root and a blank password.
3) You can now use the command lspci to determine the PCI IDs for your network or storage devices. You can run lspci –help to list the valid switches for this command. In the example below, lspci -v was run and shows a LSI Logic controller with vender ID 1000 and device ID 0030. An Intel 82545EM network card is also listed with vendor ID 8086 and device IID 100f. With these devices, ESXi is able to recognize the devices and thus includes the device name. If your device is not recognized by ESXi, it will still be in the output of lspci, but will be identified an as unknown storage or network controller. Once you have collected the PCI IDs for your network and storage devices, you can check the list here to see if ESXi has a PCI ID entry for the device and if so which driver it will load for the device. If your device is not listed but is similar to other devices in simple.map, it is possible to edit oem.tgz to enable ESXi to recognize the device and load a driver for it.