Linux-Development-Sys Digest #779, Volume #7 Sun, 16 Apr 00 23:13:31 EDT
Contents:
Re: To core or not to core - You tell me (Erik Max Francis)
Re: MICROSOFT IT THRU! MICROSOFT IS THRU! ("Mark Graybill")
Re: MICROSOFT IT THRU! MICROSOFT IS THRU! ("Mark Graybill")
Re: To core or not to core - You tell me (Mark McIntyre)
Re: A beginner's question ("Esteban Soto")
Re: high resolution timers ??? (Badrinath Venkatachari)
Re: A beginner's question (Victor Wagner)
Re: Simple but confusing C code query... (Victor Wagner)
cli() & sti()... (Badrinath Venkatachari)
Kernel update (Chuck)
Re: To core or not to core - You tell me (Erik Max Francis)
Re: cli() & sti()... (Johan Kullstam)
Re: THE SKY IS FALLING! THE SKY IS FALLING! Was (Re: MICROSOFT IT THRU! MICROSOFT
IS THRU! (Machine-gun Kelly)
Re: cli() & sti()... (Kaz Kylheku)
newbie (customer)
----------------------------------------------------------------------------
From: Erik Max Francis <[EMAIL PROTECTED]>
Crossposted-To: comp.lang.c,comp.unix.solaris,comp.lang.c++,comp.unix.programmer
Subject: Re: To core or not to core - You tell me
Date: Sun, 16 Apr 2000 15:02:31 -0700
Michael Rubenstein wrote:
> This program
> could be translated to simply store the bit pattern 0x1010 in x
> and 0x2020 in y. Which of these is the representation of the
> null pointer constant?
In fact it's worse than that -- the compiler can optimize away those
variables entirely, so the program could end up not containing any form
of null pointers anywhere.
--
Erik Max Francis | email [EMAIL PROTECTED] | icq 16063900
Alcyone Systems | web http://www.alcyone.com/max/ | q3a Product
San Jose, CA | languages en, eo | icbm 37 20 07 N 121 53 38 W
USA | 970.74 Ms p.L. | 259 days left | &tSftDotIotE
__
/ \ Many would be cowards if they had courage enough.
\__/ Thomas Fuller
------------------------------
Reply-To: "Mark Graybill" <[EMAIL PROTECTED]>
From: "Mark Graybill" <[EMAIL PROTECTED]>
Crossposted-To:
comp.os.linux.advocacy,comp.os.ms-windows.advocacy,comp.os.ms-windows.nt.advocacy,comp.os.linux.networking,comp.os.linux.security,comp.os.ms-windows.networking.tcp-ip,alt.conspiracy.area51
Subject: Re: MICROSOFT IT THRU! MICROSOFT IS THRU!
Date: Sun, 16 Apr 2000 22:48:57 GMT
Chad Myers wrote in message ...
>2.) That dll only has one error: a buffer overrun which was found after WSJ
> started this whole hype trip (that you fell for hook, line and sinker)
>3.) However, it was found that if you do not set permissions correctly for
> web publishing, it's POSSIBLE (although not likely) that someone could
> read files from another user's account. Note that this has NOTHING to
> do with that DLL files, this is just Permissioning 101.
There may be more to it, but regardless of their findings we can never prove
original intent, and Microsoft has been known to lie for awhile (e.g. IBM
forced them to recant a false public statement about 7 or 8 years ago that
damaged OS/2.) However, why waste time arguing about it (unless you are
enjoying yourselves.) :)
"Microsoft is investigating the possibility that the vulnerability would
allow a malicious user to run code of his choice on the server as well."
http://www.microsoft.com/technet/security/bulletin/fq00-025.asp
-Mark
------------------------------
Reply-To: "Mark Graybill" <[EMAIL PROTECTED]>
From: "Mark Graybill" <[EMAIL PROTECTED]>
Crossposted-To:
comp.os.linux.advocacy,comp.os.ms-windows.advocacy,comp.os.ms-windows.nt.advocacy,comp.os.linux.networking,comp.os.linux.security,comp.os.ms-windows.networking.tcp-ip,alt.conspiracy.area51
Subject: Re: MICROSOFT IT THRU! MICROSOFT IS THRU!
Date: Sun, 16 Apr 2000 22:49:59 GMT
abraxas wrote in message <8ddaep$1k8d$[EMAIL PROTECTED]>...
>In comp.os.linux.advocacy News-Only <[EMAIL PROTECTED]> wrote:
>Chad doesnt know--chad is a liar. Chad mindlessly defends microsoft with
>meaningless arguments and downright lies. Then he gets offended when (once
>again) no one believes him.
>
>Hes your average winvocate.
Hm. Who employs him?
------------------------------
From: Mark McIntyre <[EMAIL PROTECTED]>
Crossposted-To: comp.lang.c,comp.unix.solaris,comp.lang.c++,comp.unix.programmer
Subject: Re: To core or not to core - You tell me
Date: Sun, 16 Apr 2000 23:45:17 +0100
Reply-To: [EMAIL PROTECTED]
On Sun, 16 Apr 2000 08:31:36 -0400, Michael Rubenstein
<[EMAIL PROTECTED]> wrote:
>On Fri, 14 Apr 2000 23:27:07 +0100, Mark McIntyre
><[EMAIL PROTECTED]> wrote:
>
>>On Fri, 14 Apr 2000 01:02:17 GMT, [EMAIL PROTECTED] (Kaz
>>Kylheku) wrote:
>>
>>>On Fri, 14 Apr 2000 00:08:23 +0100, Mark McIntyre <[EMAIL PROTECTED]>
>>>wrote:
>>>>On Wed, 12 Apr 2000 15:33:17 -0700, Erik Max Francis <[EMAIL PROTECTED]>
>>>>wrote:
>>>>
>>>>>Mark McIntyre wrote:
>>>>>
>>>>>> Agreed. I'm talking about NULL, the macro which 6.3.2.3 and 7.17 in
>>>>>> the ANSI/ISO C standard defines as the null pointer constant.
>>>>>
>>>>>But you said "the bit pattern of NULL," which doesn't make sense,
>>>>>because NULL is a macro. Macros don't have bit patterns.
>>>>
>>>>But the macro preprocesses out to a value. And that value is either an
>>>>integer 0 or such an expression cast to a void*. This value is
>>>>represented in memory by some bitpattern.
>>>
>>>Read my other posting about this. The value of an expression is not
>>>necessarily represented in memory.
>>
>>Uhh, we had this discussion a few months back. No matter what,
>>eventually it _has_ to be in memory somewhere, even if its only in a
>>register. The processor cannot use it unless it exists somewhere...
>
>I can't find this in the standard. Can you give a citation?
What, in the _C_ standard, a definition of how processors work? Ho
hum.
>Consider the program:
>
> #include <stdio.h>
> int main(void)
> {
> int* x = NULL;
> double* y = NULL;
> return 0;
> }
>
>Suppose we have a machine on which the void* null pointer is
>represented by the bit pattern 0xf0f0, the int* null pointer by
>0x1010, and the double* null pointer by 0x2020. This program
>could be translated to simply store the bit pattern 0x1010 in x
>and 0x2020 in y. Which of these is the representation of the
>null pointer constant?
eh?
None of them because by definition NULL is 0 or (void*)0.
Mark McIntyre
C- FAQ: http://www.eskimo.com/~scs/C-faq/top.html
------------------------------
From: "Esteban Soto" <[EMAIL PROTECTED]>
Crossposted-To: comp.os.linux.development,comp.os.linux.development.apps
Subject: Re: A beginner's question
Date: Sun, 16 Apr 2000 19:14:54 -0300
Be carefull with the filenames, IE4 will dounload
"tarball-1.0.tar.gz" and name it something like "tarball-1_0_tar_tar " also
i've had trouble whith
capital letters i downloaded a bunch of files on Win98 and then when i
copied them to linux could
not compile because the caps where wrong, i.e a file that should have been
"CONFIG.H"
was named config.h.
[EMAIL PROTECTED] escribi� en mensaje
<[EMAIL PROTECTED]>...
>In comp.os.linux.development.apps Jason Rizer <[EMAIL PROTECTED]> wrote:
>> Finally, the machine on which
>> I'm running Linux is not connected to the internet, though I have a
>> machine running NT which is. Will I have a problem downloading files
>> onto the NT machine and transferring them to the Unix machine via floppy
>> or a zip disk. Thanks in advance for any help I get.
>
>Linux can read dos/fat/vfat, so you'll have no trouble reading floppies.
>
Esteban
------------------------------
From: Badrinath Venkatachari <[EMAIL PROTECTED]>
Subject: Re: high resolution timers ???
Date: Sun, 16 Apr 2000 19:14:59 -0700
Hi,
Thanks a lot for the reply. I was going through the kernel sources and quite
obviously found that there is a lot of dependency on the value of HZ. Are
there any issues that I have to be careful about before I go ahead and change
it...though the only reason I would want to change it is so that the
timer-function that I mentioned earlier wakes up more frequently.
thanks and regards
badri
Robert Redelmeier wrote:
> Badrinath Venkatachari wrote:
> >
> > Hi,
> > I have this mechanism in the kernel where I Q up read requests when
> > they
> > come in and make the processes that issued the requests sleep on a
> > wait_queue. Then the idea is to have a timer driven function dQ them at
> > regular intervals, issue the requests dQed and wake up the processes
> > waiting for the request servicing.
> >
> > Currently, I have this timer getting woken up at millisecond precision
> > (basically using jiffies with add_timer()). I would however, like to use
> > a
> > higher resolution timer for this purpose (microseconds). Is there one
> > available ???
>
> Yes, on the PC there is a Programmable Interrupt Timer living
> on certain IO ports that you can use to generate interrupts.
> IIRC, it runs at 1.19 MHz. In general, though, I would think
> the easiest thing is just to adjust HZ from the x86 default of
> 100 up to 1000 or even 10,000. Alphas run at 1000, so software
> should be variable HZ aware.
>
> -- Robert
------------------------------
From: [EMAIL PROTECTED] (Victor Wagner)
Crossposted-To: comp.os.linux.development,comp.os.linux.development.apps
Subject: Re: A beginner's question
Date: 16 Apr 2000 10:44:40 +0400
In comp.os.linux.development.apps Jason Rizer <[EMAIL PROTECTED]> wrote:
: Hello. I am a C/C++ programmer and I have recently installed Linux. I
: have no experience with Linux. I installed Redhat 6.0 from the Info
: Magic Developer's Resource CD. My question is this: Do I have a C/C++
: Compiler installed? If I don't where on the internet can I find one?
If you didn't forget to select appropriate packages during installation.
Typically you'll need at least:
1. gcc - compilier itself
2. glibc-devel - development version of system library (including header
files)
3. binutils - linker, tool for create static libraries etc.
4. make - you know what is it, aren't you
Optionally you need
g++ - C++ frontend of compilier
g77, gpc, gcj - Fortran, Pascal and Java frontends
development version of all libraries you are planning to use, such as
ncurses,
gdb - debugger
Some X11 interface to it.
Every Linux distribution includes them, but lot of people forget to
install them, and then complain to newsgroup that they cannot compile
anything.
: Any suggestions on which to choose? I'm not, at least initially,
: interested in doing any GUI development. Finally, the machine on which
: I'm running Linux is not connected to the internet, though I have a
: machine running NT which is. Will I have a problem downloading files
: onto the NT machine and transferring them to the Unix machine via floppy
With floppy - you'll definitely have a problems. Files are too big to
fit on them. Having Unix machines on both sides I'll use
tar -cMzf /dev/fd0 to create multifloppy archives, but I'm not sure that
NT version of Tar (from www.cygnus.com) is able to write on raw
floppies. Rar archiver (shareware) may help, becouse it supports
multivolume archives and available for both NT and Linux.
: or a zip disk. Thanks in advance for any help I get.
This is better. Once you are learned to distinguish between text and
binary files on NT, and tell your browser/ftp client this discinction,
it's ok.
: Jason
--
�� �������� �������� �������� �� ����������.
--- �.�. ���
------------------------------
From: [EMAIL PROTECTED] (Victor Wagner)
Crossposted-To:
uk.comp.os.linux,uklinux.help.newbies,comp.os.linux.development,comp.os.linux.questions,comp.os.linux.development.apps
Subject: Re: Simple but confusing C code query...
Date: 16 Apr 2000 10:51:59 +0400
In comp.os.linux.development.apps Michael Hopkins <[EMAIL PROTECTED]> wrote:
: Hi all,
: Please help me with this extremely simple problem.
: #include <math.h>
: int main( void )
: {
: double a = 150.0;
:
: printf(�Ok\n�); /* line A */
: printf("Log( 150 ) = %6.3f\n", log( a ) ); /* line B */
:
: return 1;
: }
: I�m using the following at the command line:
: gcc prog.c -o prog
: Some questions:
: Why does the linker tell me �undefined reference to log�? It does the
Becouse gcc doesn't include libm by default. Add -lm at the end of your
command line
: same with any of the functions that are in math.h (which is where it
: should be & is found OK, as is mathcalls.h which math.h refers to
: internally). Where is the object code for the math library routines?
In libm.so
: Why does it compile & work fine if I comment out line B? Shouldn�t I
: need to #include <stdio.h> for line A to compile?
Becouse it is really possible to use C functions without prototipes in
K&R C and gcc supports it for backword compatibility.
Try add -ansi and -pedantic options to gcc command line and may be it
would complin.
: Am I doing something very dim or are these bugs/features? Are there
: any other things I should be aware of before I undertake the Mac ->
Probably a lot. But I think you'll overcome them quitcke.
: Linux port? Can I use a command line option make the linker ignore
: functions in the included files that aren�t used in the program
I don't think so. If function is put in separate object file,
and is not called, it would be left out anyway. If it is in the same
object file, as called function, it would be linked. And it doesn't
matter how it is prototyped in include files.
: (�smart link�)? Does gcc deal with external variables in included
: files in a standard way?
What is standard way? As described in ANSI standard? Certainly.
--
The most important service rendered by the press is that of educating
people to approach printed matter with distrust.
------------------------------
From: Badrinath Venkatachari <[EMAIL PROTECTED]>
Subject: cli() & sti()...
Date: Sun, 16 Apr 2000 19:38:20 -0700
Hi,
If I happen to have this pair cli() to disable interrupts and sti() to
enable interrupts, then can it be assumed that the process cannot be
preempted while executing code in between them ???
cli()
/* code comes here */
sti()
thanks
regards
badri
------------------------------
From: Chuck <[EMAIL PROTECTED]>
Subject: Kernel update
Date: Mon, 17 Apr 2000 01:30:10 GMT
Just got Red Hat 6.2 to load on my system with it's own automatic
partitions.
Installation in Win98 partition failed.
Now I need to update my kernal and not sure how to do it.
Are you aware of a step by step guide for kernel update?
Thanks,
Chuck
--
Posted via CNET Help.com
http://www.help.com/
------------------------------
From: Erik Max Francis <[EMAIL PROTECTED]>
Crossposted-To: comp.lang.c,comp.unix.solaris,comp.lang.c++,comp.unix.programmer
Subject: Re: To core or not to core - You tell me
Date: Sun, 16 Apr 2000 18:30:39 -0700
Mark McIntyre wrote:
> What, in the _C_ standard, a definition of how processors work? Ho
> hum.
We are talking about what the C standard says about the matter, which is
all that is of any concern when it comes to null pointers _in C_.
> >Suppose we have a machine on which the void* null pointer is
> >represented by the bit pattern 0xf0f0, the int* null pointer by
> >0x1010, and the double* null pointer by 0x2020. This program
> >could be translated to simply store the bit pattern 0x1010 in x
> >and 0x2020 in y. Which of these is the representation of the
> >null pointer constant?
>
> eh?
>
> None of them because by definition NULL is 0 or (void*)0.
I suggest you read the C standard -- or at least the comp.lang.c FAQ --
before you contribute to this subject any further.
--
Erik Max Francis | email [EMAIL PROTECTED] | icq 16063900
Alcyone Systems | web http://www.alcyone.com/max/ | q3a Product
San Jose, CA | languages en, eo | icbm 37 20 07 N 121 53 38 W
USA | 970.89 Ms p.L. | 259 days left | &tSftDotIotE
__
/ \ Never contend with a man who has nothing to lose.
\__/ Baltasar Gracian
------------------------------
Subject: Re: cli() & sti()...
From: Johan Kullstam <[EMAIL PROTECTED]>
Date: Mon, 17 Apr 2000 01:50:38 GMT
Badrinath Venkatachari <[EMAIL PROTECTED]> writes:
> Hi,
> If I happen to have this pair cli() to disable interrupts and sti() to
> enable interrupts, then can it be assumed that the process cannot be
> preempted while executing code in between them ???
>
> cli()
>
> /* code comes here */
>
> sti()
make sure you consider SMP too.
--
J o h a n K u l l s t a m
[[EMAIL PROTECTED]]
Don't Fear the Penguin!
------------------------------
Date: Sun, 16 Apr 2000 22:31:02 -0500
From: Machine-gun Kelly <[EMAIL PROTECTED]>
Crossposted-To:
comp.os.linux.advocacy,comp.os.ms-windows.advocacy,comp.os.ms-windows.nt.advocacy,comp.os.linux.networking,comp.os.linux.security,comp.os.ms-windows.networking.tcp-ip,alt.conspiracy.area51
Subject: Re: THE SKY IS FALLING! THE SKY IS FALLING! Was (Re: MICROSOFT IT THRU!
MICROSOFT IS THRU!
> >This MEANS to the STUPID and IGNORANT that the U.S. Government has ACCESS
> >to every MS equipped machine in the world and therefore they
> >CAN NOT BE TRUSTED ANYMORE!
You mean the government could be trusted in the first place?
MGK
--
"Got Zombie?"
------------------------------
From: [EMAIL PROTECTED] (Kaz Kylheku)
Subject: Re: cli() & sti()...
Reply-To: [EMAIL PROTECTED]
Date: Mon, 17 Apr 2000 02:25:15 GMT
On Sun, 16 Apr 2000 19:38:20 -0700, Badrinath Venkatachari <[EMAIL PROTECTED]>
wrote:
>Hi,
> If I happen to have this pair cli() to disable interrupts and sti() to
>enable interrupts, then can it be assumed that the process cannot be
>preempted while executing code in between them ???
>
>cli()
>
>/* code comes here */
>
>sti()
First, let's take a look at your terminology. A process executing kernel code
already cannot be preempted. So if you are looking for a way to not have your
process preempted the way you assure this is by not calling anything that will
invoke the scheduler. So long as you don't call the scheduler, you aren't
preempted.
The lack of preemptiveness does not assure mutual exclusion against other
processes under SMP, because processes can come into the kernel on another
processor. And even on uP, non-preemptiveness doesn't protect against interrupt
service routines. You should use spinlocks to protect against other processors.
Prior to SMP, cli() and sti() (or alternately, save_flags(), cli() and
restore_flags()) were the primary mechanism int he kernel to assure exclusion
against anything: for example, between a process and an interrupt service
routine. However, under SMP, this mechanism breaks down because disabling
interrupts on the local processor does not keep out other processors.
What happens is that cli() and sti() are emulated in a bletcherous way on SMP.
The point I'm trying to get to is that cli() and sti() are obsolete, legacy
operations---do not use them! Use spinlocks. The operations spin_lock_irqsave()
and spin_unlock_irqrestore() work correclty under SMP and on a uP kernel they
collapse into save_flags(); cli() and restore_flags().
For protecting shared data from concurrent access by two processes running on
separate processors, if no interrupt service routines or bottom half handlers
are involved, you can use the variants of spinlocks that do not disable and
restore interrupts.
For synchronization among processes that requires scheduling delays, you
can use semaphores or wait queues.
--
#exclude <windows.h>
------------------------------
From: customer <[EMAIL PROTECTED]>
Subject: newbie
Date: Mon, 17 Apr 2000 02:58:54 GMT
have just installed Redhat 6.1, and the installation went al right.
Now I have a few questions though.
1. Is it normal for redhat to be very slow. I know that at the moment
I have a few bugs to work out, because I get some errors (no save
yourself file?), but the OS is very slow at the moment.
2. On my screen I am getting double pictures of the windows, and if I
move my mouse the left side of the screen gets fuzzy. Does anyone know
how to stop this.
3. How do I get sound to play?
Thank you if you can help. If not you need not reply.
------------------------------
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End of Linux-Development-System Digest
******************************
