On 03.04.2025 18:20, Oleksii Kurochko wrote:

On 4/1/25 6:04 PM, Jan Beulich wrote:

On 01.04.2025 17:58, Oleksii Kurochko wrote:

On 3/31/25 6:14 PM, Jan Beulich wrote:

On 31.03.2025 17:20, Oleksii Kurochko wrote:

+        _AC(XEN_VIRT_START, UL) >> vpn1_shift;
+    const unsigned long xen_virt_end_vpn =
+        xen_virt_starn_vpn + ((XEN_VIRT_SIZE >> vpn1_shift) - 1);
+
       if ((va >= DIRECTMAP_VIRT_START) &&
           (va <= DIRECTMAP_VIRT_END))
           return directmapoff_to_maddr(va - directmap_virt_start);
   
-    BUILD_BUG_ON(XEN_VIRT_SIZE != MB(2));
-    ASSERT((va >> (PAGETABLE_ORDER + PAGE_SHIFT)) ==
-           (_AC(XEN_VIRT_START, UL) >> (PAGETABLE_ORDER + PAGE_SHIFT)));
+    BUILD_BUG_ON(XEN_VIRT_SIZE != MB(8));

Is it necessary to be != ? Won't > suffice?

It could be just > MB(2). Or perphaps >=.
= would make the build fail, wouldn't it?

I just realized that BUILD_BUG_ON() condition is compared to zero so actually everything what
will make the condition true will cause a build fail as inside it used !(condition).

???

BUILD_BUG_ON() forces a compilation error if the given condition is true. Therefore, if the condition
XEN_VIRT_SIZE != MB(2) is changed to XEN_VIRT_SIZE > MB(2), the condition will always evaluate to true
(assuming XEN_VIRT_SIZE is greater than 2 MB), which will result in a compilation error.

~ Oleksii

So it seems like we have to check for XEN_VIRT_SIZE != MB(16) and change each time when XEN_VIRT_SIZE
is increased.

I don't think so, but I need to first understand the point you make above.