On 08.10.24 17:21, Gregory Price wrote:
On Tue, Oct 08, 2024 at 05:02:33PM +0200, David Hildenbrand wrote:
On 08.10.24 16:51, Gregory Price wrote:
+int __weak set_memory_block_size_order(unsigned int order)
+{
+ return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(set_memory_block_size_order);
I can understand what you are trying to achieve, but letting arbitrary
modules mess with this sounds like a bad idea.
I suppose the alternative is trying to scan the CEDT from inside each
machine, rather than the ACPI driver? Seems less maintainable.
I don't entirely disagree with your comment. I hummed and hawwed over
externing this - hence the warning in the x86 machine.
Open to better answers.
Maybe an interface to add more restrictions on the maximum size might be
better (instead of setting the size/order, you would impose another upper
limit).
That is effectively what set_memory_block_size_order is, though. Once
blocks are exposed to the allocators, its no longer safe to change the
size (in part because it was built assuming it wouldn't change, but I
imagine there are other dragons waiting in the shadows to bite me).
Yes, we must run very early.
How is this supposed to interact with code like
set_block_size()
that also calls set_memory_block_size_order() on UV systems (assuming
there will be CXL support sooner or later?)?
So this would basically amount to a lock-bit being set in the architecture,
beyond which block size can no longer be changed and a big ol' splat
can be generated that says "NO TOUCH".
Just imagine having various users of such an interface ..
I don't wanna D:
Right, and it also doesn't make sense as explained in my other comment:
this should never apply to loaded modules. :)
--
Cheers,
David / dhildenb
