I've been looking at kernel page directory/page tables on iX86 platforms.
I noticed that when the PSE flag is 1 (page size extensions) the kernel
is mapped using 4Meg pages and they are marked with the User/Supervisor
flag set to Supervisor. This seems to be correct, since the kernel pages
are protected.
However, when the PSE flag is 0 on processors that can't handle the large
page extensions, the directory entries which point to page tables that
correspond to kernel memory are marked as User. This would seem to be
incorrect, since a task can then change the page table mappings from any
priveledge level.
I don't know why this would be, and I'm not knowledgable in the kernel
code enough to know where to look to fix it. But it seems to be a bug
unless there is a reason for this (which I can't think of)
Please CC: me on any responses since I don't subscribe to the kernel
mailing list.
Thanks,
Mark Jackson
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