Jamie Lokier <[EMAIL PROTECTED]> wrote:

> It's not XIP in ROM, but is sharing code segments in RAM in the same
> way (and same compiler options), which is critical for my application.
> It reduces no-MMU fragmentation considerably.

I know.  The ELF-FDPIC binfmt was developed alongside the revised NOMMU code.

> You say private R/O - not shared R/O?

Shared R/O must be effectively shared with the backing store, so copies are
explicitly _not_ taken.

Private and shared R/O are both capable of XIP if the backing device supports
it (as specified in mapping->backing_dev_info->capabilities by the BDI_CAP_
flags).

Note that in 2.6 both the ELF-FDPIC and FLAT binfmt drivers use private R/O
mappings for their text segments.  This permits copies of the code to be taken,
and also permits ptrace attachment to prevent copies being taken.

David
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