Thank you. You pointed me back to documentation. QNX 4.x does not page to disk. A philosophical question for a RTOS. The only available memory is RAM. That´s why I care about everything. But it offers two main process image layouts. One that ´sandwiches´ the stack between the BSS and the heap, so the stack memory must be allocated at process startup. And another that leaves the stack at the low end of the data segment, so even if hinted, the stack only grows as required. What you pointed me to. By the way, the idea behind is that managing the stack in its own segment could be prohibitive for a system without disk paging. The question was I took the QNX options verbatim from the people who made the porting, and ended with a X server which at it´s very start was ´using´ more than 4 Mb of data !!! The right answer is to change compile and linking options, so even with a generous limit, the stack would be dynamically allocated as required. Than you again ----- Original Message ----- From: "Tim Roberts" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, July 08, 2003 1:34 PM Subject: Re: Re: stack size
> On Tue, 08 Jul 2003 10:13:06 -0300, mnicolet wrote: > > > >Thank you. > >You answered me what I was expecting: no system allows for a true or full > >dynamic stack size. > > If that's your interpretation, then I'm not sure what you mean by a "full > dynamic stack size". All the operating systems he mentioned reserve address > space for a gigantic stack, but they only allocate physical memory as it is > needed. Special tricks with "guard pages" are used to determine when a new > page of physical memory needs to be added to the stack. > > >Another wording: on every system one could reach some stack limit, and > >therefore one migth care about this figure. > > Yes, of course. Memory is not infinite, even on a 4GB system. > > >So, my true question comes into scene. > >The people who ported XFree86 to QNX 4.x setted the stack size hint to the > >Watcom linker to 4 Mb ( yes, 4 Mb ) for the server. > >I am wondering why a so high figure. > > I am wondering (1) why this figure seems high to you, and (2) why you are > worried about it? The stack doesn't actually use 4MB of physical memory. It > only uses the memory that is required. > > X11 is a thoroughly modular and layered server. It nests extremely deeply -- > much more deeply than a typical application. I'm not saying 4MB is > absolutely necessary, but if cutting it to 1MB causes even a single crash, > what's the point? > > >Is there a true need for such stack size ? > > Who cares? > > -- > - Tim Roberts, [EMAIL PROTECTED] > Providenza & Boekelheide, Inc. > > > _______________________________________________ > Devel mailing list > [EMAIL PROTECTED] > http://XFree86.Org/mailman/listinfo/devel _______________________________________________ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
