Re: [PATCH v5 1/4] riscv: Move kernel mapping to vmalloc zone

On Thu, 2020-07-23 at 01:21 -0400, Alex Ghiti wrote:

quoted

works fine with huge pages, what is your problem there ? You rely on
punching small-page size holes in there ?

ARCH_HAS_STRICT_KERNEL_RWX prevents the use of a hugepage for the kernel 
mapping in the direct mapping as it sets different permissions to 
different part of the kernel (data, text..etc).

Ah ok, that can be solved in a couple of ways...

One is to use the linker script to ensure those sections are linked
HUGE_PAGE_SIZE appart and moved appropriately by early boot code. One
is to selectively degrade just those huge pages.

I'm not familiar with the RiscV MMU (I should probably go have a look)
but if it's a classic radix tree with huge pages at PUD/PMD level, then
you could just degrade the one(s) that cross those boundaries.

Cheers,
Ben.