Re: [PATCH 0/13] maps: pagemap, kpagemap, and related cleanups

On Fri, Apr 13, 2007 at 10:15:24AM +1000, Nick Piggin wrote:
Andrew Morton wrote:
On Thu, 12 Apr 2007 16:10:50 -0700
William Lee Irwin III <wli@xxxxxxxxxxxxxx> wrote:

+ while (count > 0) {
+ chunk = min_t(size_t, count, PAGE_SIZE);
+ i = 0;
+
+ if (pfn == -1) {
+ page[0] = 0;
+ page[1] = 0;
+ ((char *)page)[0] = (ntohl(1) != 1);


OK.


+ ((char *)page)[1] = PAGE_SHIFT;


OK.

Shouldn't we just expose page size and endianness by other means? (another
file or
syscall).

If I send you this file dumped from a random machine, you won't know
what to make of it.

I'm planning to write a trivial server to sit on, say, my embedded
target and spew this over the wire to a client.

Not a good idea to expose raw flags in this manner - it changes at the drop
of a hat. We'd need to also expose the kernel's PG_foo-to-bitnumber
mapping to make this viable.

I don't think it is viable because that makes the flags part of the
userspace ABI. I wonder what they are needed for.

Basically: to show what the hell's going on in the VM.

--
Mathematics is the supreme nostalgia of our time.
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