Messages in this thread | | | Date | Fri, 13 Apr 2007 11:01:41 +1000 | From | Nick Piggin <> | Subject | Re: [PATCH 0/13] maps: pagemap, kpagemap, and related cleanups |
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Matt Mackall wrote: > 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@holomorphy.com> 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.
That's a good reason ;)
> 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.
kprobes / systemtap isn't good enough?
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