From mboxrd@z Thu Jan 1 00:00:00 1970 From: gaspa@yattaweb.it (Gasparini Andrea) Date: Fri, 23 Sep 2011 17:22:12 +0200 Subject: What's wrong on this mmap() ? In-Reply-To: <201109231350.08326.gaspa@yattaweb.it> References: <201109231350.08326.gaspa@yattaweb.it> Message-ID: To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org Hi, On Fri, Sep 23, 2011 at 1:50 PM, Andrea Gasparini wrote: > Hi, > I'm having some problem understanding how mmap really works. > > I have a (dummy) driver that allocate some memory (4k), and gives it to a > userspace through mmap() - the usual remap_pfn_pages found in every > example. > > The userspace can read the memory correctly, but can't write to it. (though > it maps with PROT_WRITE) > As the manpage says: PROT_WRITE - Pages may be written. Aerhm. If opened with O_RDRW and mapped with MAP_SHARED it works as expected :) Sorry for the silly question. Bye! -- - Andrea Gasparini - ----------------------------------------------- -------- https://launchpad.net/~gaspa --------- ----- HomePage: http://gaspa.yattaweb.it ------