It is possible for a pointer to represent physical memory of the same size. In other words, a 32 bit pointer can represent 32 bit addressable physical memory. Thus, issue a compilation failure only when the count of physical address bits is greater than BITS_PER_LONG (ie count of bits in void*).
Signed-off-by: Ayan Kumar Halder <[email protected]> --- Currently this change will not have any impact on the existing architectures. The following table illustrates PADDR_BITS vs BITS_PER_LONG of different archs ------------------------------------------------ | Arch | PADDR_BITS | BITS_PER_LONG | ------------------------------------------------ | Arm_64 | 48 | 64 | | Arm_32 | 40 | 32 | | RISCV_64 | Don't know | 64 | | x86 | 52 | 64 | ------------------------------------------------- However, this will change when we introduce a platform (For eg Cortex-R52) which supports 32 bit physical address and BITS_PER_LONG. Thus, I have introduced this change as I don't see it causing a regression on any of the supported platforms. xen/common/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c index 62afb07bc6..cd390a0956 100644 --- a/xen/common/page_alloc.c +++ b/xen/common/page_alloc.c @@ -2245,7 +2245,7 @@ void __init xenheap_max_mfn(unsigned long mfn) { ASSERT(!first_node_initialised); ASSERT(!xenheap_bits); - BUILD_BUG_ON(PADDR_BITS >= BITS_PER_LONG); + BUILD_BUG_ON(PADDR_BITS > BITS_PER_LONG); xenheap_bits = min(flsl(mfn + 1) - 1 + PAGE_SHIFT, PADDR_BITS); printk(XENLOG_INFO "Xen heap: %u bits\n", xenheap_bits); } -- 2.17.1
