On Tue, Aug 02, 2022 at 12:08:36PM +0000, Yeleswarapu, Nagaradhesh wrote: > [AMD Official Use Only - General] > > > On 8/1/22 08:45, Yeleswarapu, Nagaradhesh wrote: > > > [AMD Official Use Only - General] > > > > > > Hi, > > > > > > From the config options(CONFIG_VMSPLIT_3G/2G/1G), looks like 3/1 or 2/2 or > > 1/3 split is for all the user space processes. > > > > Yeah, but only for 32bit architectures. > Thanks for your response, can you please share details on how to change memory split for a 64bit architecture? You can't. With a 64-bit kernel, you either get 47 bits (128TB) of virtual address for a 64-bit process with 4-level page tables or 56 bits (64PB) with 64-bit kernels. I believe 32-bit tasks get almost 4GB of address space when run on a 64-bit kernel, but honestly I've forgotten. > > > > > Is it possible to do 2/2 split for a specific process and let all the other > > processes use default 3/1 (user/kernel) VA split? > > > > No, it's hardcoded in the kernel compilation. What would be the use case? > We are trying to offload a task from one Host to another Host, to achieve this we are looking to change > offload process Virtual address split to 2G/2G and let other processes use default memory split(3G/1G). 32-bit kernels are still relevant? They don't even get security fixes in some cases. https://lore.kernel.org/lkml/Ys%2FkfDk7mVE09N3L@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
