stack size
May be this question is not strictly suited to this list, but I see lots of people contributing from lots of different platforms. The question regards to stack space management under different platforms, or execution models. Under my preferred platform ( QNX 4.25 ) stack space is allocated at process creation, and remains fixed until process death. Thas is so because the data segment layout leaves the heap on top, so it can grow easily. So, one must guess how much stack would be needed, and give the figure to the linker. The question is: are there some other ( not exotic, of course ) platforms that allows stack growing on demand ? i.e the stack as one segment by its own, which can be dynamically re-allocated during process lifetime ? Thank you ___ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
Re: Re: stack size
- Original Message - From: Matthieu Herrb [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, July 08, 2003 3:52 AM Subject: Re: stack size mnicolet wrote (in a message from Tuesday 8) May be this question is not strictly suited to this list, but I see lots of people contributing from lots of different platforms. The question regards to stack space management under different platforms, or execution models. On Unix-like systems (and I guess in modern MS Window too) the virtual memory system allows to allocate a large stack for each process. Real memory is used only as stack grows and as virtual addresses need to have real memory pages vired to them. There still is a physical fixed stack size limit, but it's generally set quite high. I don't know any system without shared memory that would behave this way. In VxWorks you specify the stack size at task creation and it's allocating memory from the global pool. I forget to mention: QNX does use virtual memory, ( reliyng on the processor for actual memory management ) but no disk paging. So it behaves like VxWorks, i.e, early and _true_ stack allocation. Matthieu Thank you. You answered me what I was expecting: no system allows for a true or full dynamic stack size. Another wording: on every system one could reach some stack limit, and therefore one migth care about this figure. 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 tried to grep the sources searching for some form of alloca usage ( the native one or a home brew, Postgresql style ) without success. In fact, all what is malloc and free related is coded using macros, which even appear redefined for some modules. But what I cannot figure simply is the possible recursions, and/or giant local objects. Is there a true need for such stack size ? marcelo ___ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
Re:: Re: stack size
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
Re: twm makes uninitialized memory access after malloc()
Some time ago, I posted a question regarding twm crash. I was not able to reproduce it after, but I don´t played more than a few minutes. Later, some one told me that twm is inherently weak, and pointed me to fvwm. My concern was mainly because I am new to X Windows, and I was fearing regarding my build of XFree86 4.2.0 ( even if all went ok with make World after two or three minor hacks ). I build and intend to use it on a QNX 4.25 platform which has some departures from a standard *NIX: lack of UNIX sockets ( only INET ) and lack of shared libraries. Also, because other questions I build the whole thing using register calling convention. So, the crash of twm troubled me. But it must be noted that the crash happened after some time of execution, not at the very start. Regards M Nicolet - Original Message - From: Egbert Eich [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, July 04, 2003 9:50 AM Subject: twm makes uninitialized memory access after malloc() We have a report in Bugzilla (#464), concerning twm. This test can only be made on NetBSD: === if you set /etc/malloc.conf to AJ (fill malloc'ed region with random value), twm crashes occasionary. i'm yet to find out a concrete way to repeat the symptom, however, it seems that twm (or some library) is touching malloc'ed memory region without initialization. === Could somebody with NetBSD please try to reproduce this? I'd at least need a debugger backtrace to get a clue where the problem may be. Egbert. ___ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel ___ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
Re: twm stop run
Hello Frank Thank you for your answer to the twm question. I am considering fvwm, but I was urged to test fltk. And that urgency was because before of fltk, I tried FOX, with all tests SIGSEGVing at the very start. So, I was doubting regarding my compilation environment for X. I was trying to contact you or another qnx port team member to ask some basic questions. If you don´t take this as abuse, now that I know your mailbox, I would like to ask those again, and directing this mail to you and not the list, because I think this is very specific to QNX 4.x. I tried first the binary distribution from the jcmichot page, but that failed to run, ( later I learned why : it was trying to open a unix socket for local connections ), then I compiled XFree86 4.2 from source, under these restrictions: 1) I don´t have libcrypt, only login, and only in 3r ( login3r.lib ). 2) I have only TCP/IP 4.23 and 4.25 run times, so, no Unix sockets. Then, I adapted QNX4.cf to this environment, eliminating UNIXCONN and changing compiling options to -5r. Also, I needed to ´touch´ some sources and makefiles ( If you consider these interesting, I can post you the changes - in fact, one is to my judge, very important ). All went ok, and, as you could see from my posting to the list, I have a functional X environment. But some questions arise 1 - the most intriguing: why the so big stack ( if you remember, QNX4.cf forces XFree86 linking to -N4096000 ). I tried to figure out if some modules are using alloca, but the allocation coding is so deep wrapped with macros ( also redefined ) that it proves a useless or unsure path. So, I am asking to the people who knows. The main question is that under the QNX 4 execution model, the stack is allocated as hinted, even if the process don´t need all the space. After a while, the data segment continues to grow - some 1 Mb more, I guess. This is ok, because obviously, some data is allocated from heap. But I am asking me if the stack remains largely unused. 2 - from the binary distribution, I see some clients ( xqsh, by example ) whose sources are not in the source tree from xfree.org. Is there a way to get those specific QNX clients sources ? Of course, the main question is keyboard management, I guess. 3 - Some more general xfree distribution question: I noted that cpp is not in the source tree. Thankfully, I had it from the binary previously installed. How could I obtain the source ? Thank you in advance Regards Marcelo Nicolet - Original Message - From: Frank Liu [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, June 09, 2003 1:59 AM Subject: Re: twm stop run possibly a twm bug, I would suggest trying another window manager like fvwm. ___ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
twm stop run
Hello I am a newbie to X. I compiled from source the 4.2 version, on QNX 4.25, using TCP/IP 4.23 suite, with Watcom 10.6. All works fine, except when I was testing fltk 1.1.4rc1. Running one of the tests, ( specifically, the ´tile´ test/demo for those who know the toolkit ) suddenly all twm decorations gone, leaving all windows intact. Also, a previous test window appeared. Of course, a ps run showed that twm was not running. I could shutdown all the thing normally, because my last xterm was in the foreground. Later, I tried to reproduce the behaviour, with no success. Also, I redirected twm´s stdout and stderr to files trying to catch some error message. What I don´t know if this may be a twm ´glitch´ ( flaw ? ) or a fltk one. Could someone help me regarding a) How to catch twm errors/warnings ( is there a specific log option ? ) b) Has twm some known weaknesses ? c) migth the twm failure be caused by a XFree86 misbehaviour due to my specific platfform/compile combination ? which one (s) ? d) has the fltk toolkit some known flaws ? ___ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
qnx 4.x porting
Hello This mail is mainly for the people that made the QNX4 porting, but may be someone may help. I am a newbie to X. I downloaded and successfully installed XFree86 R6, Version 4.2.0 on QNX 4.25, using Watcom 10.6 Patch B from QSSL. I managed to run it even on TCP/IP 4.23 ( no unix sockets ) by ´telling´ the server not to use UNIXCONN, but only TCPCONN. Also, because I don´t have crypt, nor login3s.lib ( only the 3r version ) I changed the related option to wcc, by using -5r, and changing the -l option to that library. My question regards about the ´giant´ stack size for the Xserver: 4 Mb is a lot ! and I am intrigued why this enormous stack. I tried to dive the sources for an intensive use of alloca, but to no clear result. Could someone ( the QNX porting authors, or someone else ) tell me if I can confidently reduce the stack size, and in such a case, which should be a reasonable figure ? Note, for not QNX/Watcom users: the -xr ( i.e, -5r ) tells the compiler to generate functions calls using registers where possible, as opposed to -xs, which directs it to only use the stack for argument passing. With all the code generated this way, the stack usage is greatly reduced. So, the only source for a big stack need could come from very large/deep recursive calls, from large locals, or from alloca usage. Thank you Marcelo Nicolet PS. Incidentally ... when compiling in -xr mode, Watcom reports an error whenever a function call does not follows the prototype ( except, of course, it´s declared as variadic ). This was the case in lib/X11/omGeneric.c, line 1129, when calling parse_fontdata( ), which I easily corrected adding a dummy FontDataRec argument. PS2. For those potentially interested: Aside the correction mentioned above, I made another important one ( again, Watcom stuff ) to .../BUSmemcpy.c, and to a few Makefiles. The changes are somewhat brute force, so I am not sure how I can contribute them to the main source tree. ___ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
