> +/*
> + * Platforms should define arch_get_mappable_range() that provides
> + * maximum possible addressable physical memory range for which the
> + * linear mapping could be created. The platform returned address
> + * range must adhere to these following semantics.
> + *
> + * - range.start <= range.end
> + * - Range includes both end points [range.start..range.end]
> + *
> + * There is also a fallback definition provided here, allowing the
> + * entire possible physical address range in case any platform does
> + * not define arch_get_mappable_range().
> + */
> +struct range __weak arch_get_mappable_range(void)
> +{
> + struct range memhp_range = {
> + .start = 0UL,
> + .end = -1ULL,
> + };
> + return memhp_range;
> +}
> +
> +struct range memhp_get_pluggable_range(bool need_mapping)
> +{
> + const u64 max_phys = (1ULL << (MAX_PHYSMEM_BITS + 1)) - 1;
Sorry, thought about that line a bit more, and I think this is just
wrong (took me longer to realize as it should). The old code used this
calculation to print the limit only (in a wrong way), let's recap:
Assume MAX_PHYSMEM_BITS=32
max_phys = (1ULL << (32 + 1)) - 1 = 0x1ffffffffull;
Ehm, these are 33 bit.
OTOH, old code checked for
if (max_addr >> MAX_PHYSMEM_BITS) {
Which makes sense, because
0x1ffffffffull >> 32 = 1
results in "true", meaning it's to big, while
0xffffffffull >> 32 = 0
correctly results in "false", meaning the address is fine.
So, this should just be
const u64 max_phys = 1ULL << MAX_PHYSMEM_BITS;
(similarly as calculated in virito-mem code, or in kernel/resource.c)
> + struct range memhp_range;
> +
> + if (need_mapping) {
> + memhp_range = arch_get_mappable_range();
> + if (memhp_range.start > max_phys) {
> + memhp_range.start = 0;
> + memhp_range.end = 0;
> + }
> + memhp_range.end = min_t(u64, memhp_range.end, max_phys);
> + } else {
> + memhp_range.start = 0;
> + memhp_range.end = max_phys;
> + }
> + return memhp_range;
> +}
> +EXPORT_SYMBOL_GPL(memhp_get_pluggable_range);
--
Thanks,
David / dhildenb
