From mboxrd@z Thu Jan 1 00:00:00 1970 From: mulyadi.santosa@gmail.com (Mulyadi Santosa) Date: Sat, 28 May 2011 01:01:57 +0700 Subject: Can we map a device address to two different memory locations? In-Reply-To: References: Message-ID: To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org On Sat, May 28, 2011 at 00:48, anish singh wrote: > > > On Fri, May 27, 2011 at 10:54 PM, Mulyadi Santosa > wrote: >> >> Hi... >> >> On Fri, May 27, 2011 at 17:49, sandeep kumar >> wrote: >> > Now the question is can we memory map a one device resource(say some >> > iomemory) to two different memory locations? >> > the other way of seeing at this question is, >> > Will ioremap() gives different 'virtual addresses' when called multiple >> > times? >> >> I agree with Daniel, but I suggest you to think about it: in reading >> operation, maybe it's ok, no concurrency issues need to be taken >> care...but how about writing? unless we're sure they are atomically or >> uninterruptible, i see a chance that race condition might happen here. >> >> Actually it's similar when you map a file into two different VMA and >> write into it, correct? > > Don't you think it would also be reducing the memory map space in RAM > which is a critical resource and many other?drivers?would be denied > the mapping of there IO resources? Yeah, I agree too -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com