The SATA_SIL24 driver for Sil 3124 chipset SATA is missing from the Alpha install CD. All my Alpha systems have a Sil 3124 card, and I cannot install Gentoo on them without this driver.
I've pinged armin76, who maintains our kernel configs, and asked that he add CONFIG_SATA_SIL24. (I would have seen this sooner if alpha@ had been Cc'd)
Fantastic, thank you so much.
New kconfig pushed to the repo. Will close this bug when a new installcd has been built.