Kernel2.6.31以降で起動しなくなりました。
ata3: softreset failed (device not ready)
ata3: failed due to HW bug, retry pmp=0
ata5: softreset failed (device not ready)
ata5: failed due to HW bug, retry pmp=0
ここで止まります。
2.6.30-0.slh.4-sidux-amd64は無事にスキップするようで起動します。

http://forums.gentoo.org/viewtopic-t-756146-start-0.html
どうもATIのハードウェアに問題があるようでカーネル開発側としては
ハードのアグだから無視という感じだそうですが
起動しなくなったのは2.6.31以降のカーネルの変更でしょうか？siduxカーネル独自の変更でしょうか？

lspciの結果です
00:00.0 Host bridge: ATI Technologies Inc RS690 Host Bridge
00:02.0 PCI bridge: ATI Technologies Inc RS690 PCI to PCI Bridge (PCI Express Graphics Port 0)
00:12.0 SATA controller: ATI Technologies Inc SB600 Non-Raid-5 SATA
00:13.0 USB Controller: ATI Technologies Inc SB600 USB (OHCI0)
00:13.1 USB Controller: ATI Technologies Inc SB600 USB (OHCI1)
00:13.2 USB Controller: ATI Technologies Inc SB600 USB (OHCI2)
00:13.3 USB Controller: ATI Technologies Inc SB600 USB (OHCI3)
00:13.4 USB Controller: ATI Technologies Inc SB600 USB (OHCI4)
00:13.5 USB Controller: ATI Technologies Inc SB600 USB Controller (EHCI)
00:14.0 SMBus: ATI Technologies Inc SBx00 SMBus Controller (rev 14)
00:14.1 IDE interface: ATI Technologies Inc SB600 IDE
00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA)
00:14.3 ISA bridge: ATI Technologies Inc SB600 PCI to LPC Bridge
00:14.4 PCI bridge: ATI Technologies Inc SBx00 PCI to PCI Bridge
00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration
00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map
00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller
00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control