On 05.12.2022 10:48, Ayan Kumar Halder wrote: > In the near future, we are considering to use a common xen/domain heap for > Arm 32-bit V8-R. In this setup, both PADDR_BITS and BITS_PER_LONG will be > 32. Therefore, the condition PADDR_BITS >= BITS_PER_LONG will become true. > > Looking at the commit that introduce the BUILD_BUG_ON (88e3ed61642b > "x86/NUMA: make init_node_heap() respect Xen heap limit") and the current > use, it seems this check was mainly to ensure that the shift of xenheap_bits > is not going to be undefined (>> N for a N-bit type is undefined). > > So far, all the shifts are using "xenheap_bits - PAGE_SHIFT". Therefore, the > existing code should work for 32-bit architecture as long as the result of > the substraction is below 32. > > Therefore relax the BUILD_BUG_ON() to check that (PADDR_BITS - PAGE_SHIFT) > is not equal of above BITS_PER_LONG. > > Note that we would need further precaution if we ended up to use > 'xenheap_bits' alone in shifts. > > Signed-off-by: Ayan Kumar Halder <[email protected]> > Signed-off-by: Julien Grall <[email protected]>
Acked-by: Jan Beulich <[email protected]>
