The /highentropyva compiler option tells the Windows kernel whether a particular executable supports high entropy Address Space Layout Randomization (ASLR).
/highentropyva[+ | -]
This option specifies that a 64-bit executable or an executable that is marked by the /platform:anycpu compiler option supports a high entropy virtual address space. The option is disabled by default. Use /highentropyva+ or /highentropyva to enable it.
The /highentropyva option enables compatible versions of the Windows kernel to use higher degrees of entropy when randomizing the address space layout of a process as part of ASLR. Using higher degrees of entropy means that a larger number of addresses can be allocated to memory regions such as stacks and heaps. As a result, it is more difficult to guess the location of a particular memory region.
When the /highentropyva compiler option is specified, the target executable and any modules that it depends on must be able to handle pointer values that are larger than 4 gigabytes (GB) when they are running as a 64-bit process.