[PATCH v5 1/4] riscv: Move kernel mapping to vmalloc zone
benh at kernel.crashing.org
Thu Jul 23 18:33:12 EDT 2020
On Thu, 2020-07-23 at 01:21 -0400, Alex Ghiti wrote:
> > 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.
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