“The Bigmem kernel (kernel-bigmem) is an additional Linux kernel available for SLES for SAP Applications 11 SP4 customers through the maintenance channel.
The Bigmem kernel is modified to provide support for up to 32TB on IBM POWER. Customers using SAP HANA can optionally use the Bigmem kernel to support any size memory up to 32TB.
Customers who are using SLES 11 for workloads other than SAP HANA will continue to use the standard kernel.
Moving forward, both kernels will be supported by SUSE on SLES for SAP Applications 11 SP4.

– The standard kernel-default is only certified for configurations up to 1.5TB and should be not used for larger installations.
– The kernel-bigmem is only supported for SAP HANA environments when running SUSE Linux Enterprise Server for SAP Applications 11 SP4 (ppc64)
– The kernel-bigmem is NOT supported when running the standard SUSE Linux Enterprise Server 11 SP4 4 (ppc64) or for workloads other than SAP HANA.

The Bigmem kernel also increases the number of threads supported by SLES for SAP Applications 11.
This is required for systems that have more than 1024 logical CPUs such as an IBM Power System E880 configured with 192 physical CPU core with SMT8, resulting in 1536 logical CPU threads.

Also, note that clients implementing SAP HANA on SLES for SAP Applications 12 do not need the Bigmem kernel because the base kernel in SLES 12 already supports up to 32 TB of memory.”

Source:
https://kruemcke.wordpress.com/2017/02/13/more-memory-now-available-for-sap-hana-on-sles-11-for-power/
https://www.suse.com/de-de/support/kb/doc/?id=7018408

current restrictions with HoP:
2188482 – SAP HANA on IBM Power Systems: Allowed Hardware
2055470 – HANA on POWER Planning and Installation Specifics – Central Note
2271345 – Cost-Optimized SAP HANA Hardware for Non-Production Usage
2230704 – SAP HANA on IBM Power Systems with multiple – LPARs per physical host