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volatile unsigned long cpu_online_map vs unsigned long cpu_online_map

Linux-ia64 Bill Nottingham 4 participants 7 messages Jun 26, 2001

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Bill Nottingham

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#0 lore raw
Quoted 6 lines · David Mosberger

Andreas> include/asm-ia64/smp.h has 'extern unsigned long Andreas> cpu_online_map', but arch/ia64/kernel/setup.c and Andreas> arch/ia64/kernel/smpboot.c have 'volatile unsigned long Andreas> cpu_online_map'. Which one is correct?

It should be volatile.

Also, shoudn't it be extern in at least one of setup.c/smpboot.c?

Bill

#1 lore raw

Bill Nottingham <[email protected]> writes:

|> David Mosberger ([email protected]) said: 
|> >   Andreas> include/asm-ia64/smp.h has 'extern unsigned long
|> >   Andreas> cpu_online_map', but arch/ia64/kernel/setup.c and
|> >   Andreas> arch/ia64/kernel/smpboot.c have 'volatile unsigned long
|> >   Andreas> cpu_online_map'.  Which one is correct?
|> > 
|> > It should be volatile.
|> 
|> Also, shoudn't it be extern in at least one of setup.c/smpboot.c?

No. The definition in setup.c is guarded by CONFIG_SMP, and smpboot.c is not use on non-SMP.

Andreas.

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Andreas Schwab                                  "And now for something
SuSE Labs                                        completely different."
[email protected]
SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg
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#2 lore raw
In reply to Bill Nottingham
Quoted 4 lines · Andreas Schwab

|> Also, shoudn't it be extern in at least one of setup.c/smpboot.c?

No. The definition in setup.c is guarded by CONFIG_SMP, and smpboot.c is not use on non-SMP.

But then on a SMP kernel you have two definitions of the same symbol, yes?

Bill

#3 lore raw

RE: [Linux-ia64] Re: volatile unsigned long cpu_online_map vs uns

In reply to Bill Nottingham

cpu_online_map gets used and defined only for SMP configurations. We will need to remove the definition of cpu_online_map from setup.c as it is defined in smpboot.c. For setup.c, cpu_online_map is done extern in smp.h (...change to volatile there..)

Below is the patch for setup.c

tmp/setup.c Tue Jun 26 09:46:40 2001 renamed from setup.c Fri Jun 1 15:15:53 2001 +0 -4
@@ -60,10 +60,6 @@
 /* This tells _start which CPU is booting.  */
 int cpu_now_booting;
 
-#ifdef CONFIG_SMP
-volatile unsigned long cpu_online_map;
-#endif
-
 unsigned long ia64_iobase;     /* virtual address for I/O accesses */
 
 #define COMMAND_LINE_SIZE      512

-----Original Message-----
From: Andreas Schwab [mailto:[email protected]]
Sent: Tuesday, June 26, 2001 9:57 AM
To: David Mosberger
Cc: [email protected]
Subject: [Linux-ia64] Re: volatile unsigned long cpu_online_map vs unsigned long cpu_online_map

Bill Nottingham <[email protected]> writes:

|> David Mosberger ([email protected]) said: 
|> >   Andreas> include/asm-ia64/smp.h has 'extern unsigned long
|> >   Andreas> cpu_online_map', but arch/ia64/kernel/setup.c and
|> >   Andreas> arch/ia64/kernel/smpboot.c have 'volatile unsigned long
|> >   Andreas> cpu_online_map'.  Which one is correct?
|> > 
|> > It should be volatile.
|> 
|> Also, shoudn't it be extern in at least one of setup.c/smpboot.c?

No. The definition in setup.c is guarded by CONFIG_SMP, and smpboot.c is not use on non-SMP.

Andreas.

Signature · 10 lines
Andreas Schwab                                  "And now for something
SuSE Labs                                        completely different."
[email protected]
SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5

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#4 lore raw
In reply to Bill Nottingham

Bill Nottingham <[email protected]> writes:

|> Andreas Schwab ([email protected]) said: 
|> > |> Also, shoudn't it be extern in at least one of setup.c/smpboot.c?
|> > 
|> > No.  The definition in setup.c is guarded by CONFIG_SMP, and smpboot.c is
|> > not use on non-SMP.
|> 
|> But then on a SMP kernel you have two definitions of the same
|> symbol, yes?

Yes, you are right, I got the logic wrong.

Andreas.

Signature · 5 lines
Andreas Schwab                                  "And now for something
SuSE Labs                                        completely different."
[email protected]
SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
#5 lore raw
In reply to Bill Nottingham
Quoted 1 line
Quoted 1 line
Quoted 1 line
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Quoted 1 line · Bill Nottingham

Bill> Also, shoudn't it be extern in at least one of Bill> setup.c/smpboot.c?

I already have taken care of that in the latest source tree. I don't think it causes any problems.

	--david
#6 lore raw
In reply to Bill Nottingham

David Mosberger <[email protected]> writes:

|> >>>>> On Tue, 26 Jun 2001 12:24:20 -0400, Bill Nottingham <[email protected]> said:
|> 
|>   Bill> Also, shoudn't it be extern in at least one of
|>   Bill> setup.c/smpboot.c?
|> 
|> I already have taken care of that in the latest source tree.  I don't
|> think it causes any problems.

Only if you compile the kernel with -fno-common.

Andreas.

Signature · 5 lines
Andreas Schwab                                  "And now for something
SuSE Labs                                        completely different."
[email protected]
SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5