Compact Flash compatibility issues

[kethd]

This is most detailed discussion I have seen about Compact Flash sometimes working and sometimes not as IDE. Please add any other good resources you find.

http://www.openbrick.org/wiki/cf/FrontPage
Compact Flash Chipset
* Toshiba does IDE/CF controlers which are incompatible with DMA mode operation of a HD on the same BUS
* Hitachi seems to do CF/IDE controlers which work with OpenBrickx and DMA mode
* Lexar apparently make good controlers which work in BK level
* Samsung does CF/IDE chipsets which are totally incompatible with the OpenBrickx
Compact Flash IDE Chipset
The IDE chipset will determine the level of compatibility of a CF card, in particular for DMA mode....

notes from the Linux IDE kernel author Mark Lord !!!
http://www.openbrick.org/en/Members/jp/udma/view
*** What is known to work
- A compact flash card alone set as master or as slave. The OpenBrick will boot on the compact flash. It is recommended to choose the master setup for compact flash in this case.
- A hard disk alone set as master. The OpenBrick will boot on the hard disk and use UDMA without any problem (tested on Mandrake 8.2 / 9.0 Linux 2.4.18 kernel).
- A hard disk (without DMA) and a compact flash together if the kernel is patched.
*** What works more or less
- A compact flash card set as master, a hard disk set as slave. The OpenBrick boots on the compact flash (Debian kernel 2.2.20) and mounts the hard disk. However, in this case, the DMA does not always work.
*** What does not work
- Booting a hard disk set as master with a standard 2.4.18 kernel when a compact flash is inserted at the same time (master or slave). The kernel loads and can not access the hard disk.
- Booting a compact flash set as master with a standard 2.4.18 kernel and accessing a hard disk set as slave. The kernel loads but ignores the slave hard disk...

Official info:
http://www.compactflash.org/faqs/faq.htm