On Wed, Mar 3, 2021 at 12:38 PM Sebastian Huber <sebastian.hu...@embedded-brains.de> wrote: > > On 03/03/2021 19:31, Gedare Bloom wrote: > > >> Is there no guarantee that stack_size == config->stack_size? > >> > > Suppose an application requests a stack size with > > config->stack_area = m*CPU_STACK_ALIGNMENT > > config->stack_size = (n*CPU_STACK_ALIGNMENT - 1) > > > > Then, you will get > > stack_begin = config->stack_area; > > because it is already aligned > > stack_end = (n-1)*CPU_STACK_ALIGNMENT; > > for the align_down > > and the stack size you get in the end is > > (n-1)*CPU_STACK_ALIGNMENT; > > instead of > > n*CPU_STACK_ALIGNMENT-1; > > > > so you lose CPU_STACK_ALIGNMENT-1 bytes from the stack, and the user > > doesn't get back the requested number of bytes, but they also don't > > get any kind of error or status. They just lose some bytes. > > > > I think this is wrong. > > If you provide a stack, then it is up to you to provide properly aligned > areas or you loose a couple of bytes. We check that a minimum size is > met.We provide also an interface to properly align things > (RTEMS_TASK_STORAGE_ALIGNMENT). I would also not fill up the stack to > the last byte, so there will be a bit of waste anyway. > > We could add alignment checks to _RTEMS_tasks_Prepare_user_stack(), but I am > not sure if there is a real need for this. For some applications it might be > better to just waste some bytes and not align everything to avoid padding > through the linker. >
I think it is just invalid to shrink the stack size smaller than it is requested. If I call pthread_attr_setstacksize(), then "The stacksize attribute shall define the minimum stack size (in bytes) allocated for the created threads stack." I should not get back a stack size smaller than I requested when I create the pthread. It's just wrong. https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_attr_getstacksize.html > -- > embedded brains GmbH > Herr Sebastian HUBER > Dornierstr. 4 > 82178 Puchheim > Germany > email: sebastian.hu...@embedded-brains.de > phone: +49-89-18 94 741 - 16 > fax: +49-89-18 94 741 - 08 > > Registergericht: Amtsgericht München > Registernummer: HRB 157899 > Vertretungsberechtigte Geschäftsführer: Peter Rasmussen, Thomas Dörfler > Unsere Datenschutzerklärung finden Sie hier: > https://embedded-brains.de/datenschutzerklaerung/ > _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
