Hot swapping PCIe based ExpressCards with PCIe to ExpressCard Drives
This is intended to address questions regarding PCIe to ExpressCard readers. The PCI Express (PCIe) specification allows for hot-swapping of PCIe devices. Since ExpressCard is simply PCIe and USB with different connectors, it would follow that PCIe to ExpressCard adapters should inherit such behavior when installed in computers with PCIe slots. Unfortunately this isn't always the case. A system's BIOS (or firmware) and the host operating system need to treat an PCIe slot as having hot-swap capability. This behavior is taken for granted on notebook computers. When PCIe to ExpressCard drives were released, manufacturers assumed host systems would treat them the same.
Most desktop machines are not setup to hot swap on their PCIe slots. At first operating system vendors blamed BIOS makers for the problem, but recent developments seem to indicate it is not only the BIOS makers to blame. Synchrotech learned this with a desktop machine with a PCIe to ExpressCard drive (EXP54-CR-PCEIR1) installed. When the drive wouldn't hot-swap under The Windows XP, Synchrotech was told the BIOS was to blame. However, with the release of OpenBSD 4.3, our tests showed the PCIe to ExpressCard drive could hot-swap PCIe based ExpressCards without any modifications to the system's BIOS. Our conclusion is it is a combination of both the BIOS and operating system. Synchrotech is working hard to get operating system and BIOS vendors to rectify this problem. Currrently, many systems require booting with a PCIe based ExpressCard in the ExpressCard slot in order to have the card recognized.
For More Information
- Firmware Support for PCI Express Hot-Plug and Windows
- ExpressCard FAQ for ExpressCard 34 and ExpressCard 54
Possible Work Around Procedures
- With The Windows XP, many end users have reported that after inserting a PCIe based ExpressCard into a PCIe to ExpressCard drive they can evoke the 'scan for new hardware' command in the 'device manager' resulting in the ExpressCard being recognized. These finding have been confirmed by Synchrotech (with the test system mentioned above). However, we also have reports of this not working with all systems.
- With The Vista version of The Windows, Synchrotech hasn't obtained any information whether it behaves like The Windows XP.
- We currently have no solution for Mac OS X, although we would be happy to find a solution for PCIe based Mac desktops quickly. Because of the superior quality of Final Cut Pro and Mac OS X, we have had many video professionals wanting to use Sony/Sandisk's SxS ExpressCards with our PCIe to ExpressCard Drive.
- For OpenBSD, upgrading to version 4.3 seems to enable PCIe to ExpressCard hot-swap.
PCIe to ExpressCard Adapter Support Topics
- Can I 'rescan' the PCI expansion slots?
- More information about hot swapping capabilities ExpressCards under various operating systems
- ExpressCard FAQ for ExpressCard 34 and ExpressCard 54
- Answers a broad range of ExpressCard questions including form factor, compatibility, etc.
- Firmware Support for PCI Express Hot-Plug and Windows
- Microsoft document on PCIe hot-plug
- SxS PRO Device Drivers
- Information about Sony/Sandisk's SxS Pro ExpressCards
