Ray Of Hope

Embedded Linux- Different Virtual Address Same Physical Address – Not able to read & Write

Again faced a new situation in this embedded world. I implemented one user space(US_1) application which, when executed on a user space on network processor card was writing data to the shared memory.

Another user space application(US_2) compiled by my friend when executed on the same network processor card was supposed to read data from the shared memrory.

But to my surprise US_2 was unable to read the data from the memory. On further debugging , I found that virtual address assigned to US_1 and US_2 is different but physical address for the both are same.

Now I am wondering why this is happening , if US1_ and US_2 are getting the same physical addresss, then why US2 is uanble to read what US_1 is writing. And another question why its US_1 and US_2 are getting different virtual address for same physical address in embedded linux that doesn’t have any MMU. (I am using Windrvr version of linux)

Anshul Makkar, anshul_makkar@justkernel.com
Originally Posted On: 2010-05-06 04:31:01


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