Known problems for 3.5/0.5 virtual space split???

I wonder if there are any known problems for applying 
2.4.21rc8aa1 patch from Andrea?

I'm trying to boot a Xeon 2.4 box with 4GB of RAM, IDE CD and 
Adaptec AIC7XXX SCSI devices.

I compile the kernel with 1/3 split and it boots OK. When I simply 
change the split to 3.5/0.5, it gets stuck during the boot not being 
able to mount root partition.

Any ideas? Any other working kernel/patch configurations for h/w 
like I have?

Thanks
Giga