RE: [PATCH] enable to read region 5 from /dev/kmem

From: Luck, Tony <tony.luck_at_intel.com>
Date: 2005-07-13 05:05:19
>/dev/[k]mem should use the EFI memory attributes to determine
>accessibility.  This is being done to some degree already (well, I
>didn't check the current code, but it's supposed to be there).

The current code relies on checking "PageUncached(page)" to decide
whether to convert a region 7 access into a region 6 access.

But this patch would allow any address in region 6 to be accessed
(and so we'd see an MCA if the address had been cached via a
region 7 access ... or for that matter a user-mode access).

Now, I suppose we could build on this patch so that if a user tries
to access a cacheable page through region 6, we'll quietly swap it
for an cacheable access to the matching address in region 7.  But I'm
not sure whether this is really useful.  Region 6 and 7 provide
access to the same memory, but with different cache attributes.

It comes down to what the real semantics of /dev/kmem are supposed
to be.

-Tony
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Received on Tue Jul 12 15:09:03 2005

This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:40 EST