Embedded Linux System Design and Development

uClinux 367

shared. Whenever either of the two processes attempts to write into this page,

the page fault handler identifies a COW page using a special check of the

page descriptors. The page corresponding to the fault is duplicated and marked

writable in the process that attempted the write. The original page remains

write protected until the other process attempts a write, during which this

page is marked writable only after making sure that it is no longer shared

with any other process.

As seen above, process duplication in Linux done via COW is implemented

using the page fault handler and hence uClinux does not support

fork().

Also it is not possible for parent and child to have a similar virtual address

space as expected from

fork. Instead of using ...