On Tue, Sep 4, 2012 at 4:09 PM, Julian Andres Klode <jak@xxxxxxxxxxxxx> wrote: > On Tue, Sep 04, 2012 at 03:58:20PM +0530, Manavendra Nath Manav wrote: >> On Tue, Sep 4, 2012 at 3:00 PM, Manavendra Nath Manav >> <mnm.kernel@xxxxxxxxx> wrote: >> > Hi, >> > >> > I have declared a static const int variable in one driver and exported >> > that variable symbol. In another driver i am modifying that variable. > > No, you did not export it. It's static (and static is kind of the opposite > of extern). And then you try to assign a value to a non-static variable with > the same name, which might not even exist (as the other is static, this should > not even work in my opinion). > >> > The other driver prints the modified value but the original driver >> > retains the original value. When both virtual and physical addresses >> > of the variable as seen by both drivers are same, how is this even >> > possible. Is it a kernel bug? > > It only works because the compiler optimized the value = 123 away, > and replaced value with 123 in the first module everywhere, as it > is declared const and thus cannot be changed, so there's no reason > to read it from memory. > > -- > Julian Andres Klode - Debian Developer, Ubuntu Member > > See http://wiki.debian.org/JulianAndresKlode and http://jak-linux.org/. Still I am not able to understand !! Why the output behaviour changes when the declaration is made as "const volatile". I get the same results as above when i remove "static" and retain "const". -- Manavendra Nath Manav _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
