When installing SCO patch PTF 506A on an OpenServer 5.0.6 system that has the LSI Logic 
driver slha installed, the kernel link may fail with the messages:

i386ld:Symbol numHBAs in
/var/opt/K/SCO/link/1.1.1Ga/etc/conf/pack.d/slha/space.o
is multiply defined. First defined in
var/opt/K/SCO/link/1.1.1Ga/etc/conf/pack.d/slha/Driver.o
ERROR:Can not link-edit unix
system build failed
Error:kernel link failed
Error Stack:Kernel link failed

The kernel link failure is caused by a flaw in PTF 506A that replaces the LSI Logic 
driver file Driver.o with a prior version.

To resolve the situation, exit the PTF 506A installation (the kernel link is the last 
operation of the installation) and re-install the LSI Logic driver from your BTLD diskette.  Relink the kernel and reboot.  This will result in the system retaining the PTF 506A changes plus your LSI Logic driver.

SCO has this issue noted in Technical Article 117766. 