IA64_GENERIC vs. NUMA/DISCONTIG/VIRTUAL_MEM_MAP

IA64_GENERIC vs. NUMA/DISCONTIG/VIRTUAL_MEM_MAP

[dann frazier]

hey,
  It was requested that I turn on DISCONTIGMEM in my builds for Debian, in order to support
Altix boxes.  This option is not currently selectable w/ a 2.6.6 "Generic" kernel, but
it is with all other flavors.

  I dug around to see if this is intentional, and found evidence[1] that it is not.
From what I can grok from Documentation/kbuild/kconfig-language.txt, select will force
these options off - maybe "depends on" is what was intended?
I tried creating a patch w/ this change, but found that adding thse deps creates a
recursive dependency tree that breaks Kconfig, since DISCONTIGMEM depends on
(IA64_DIG || IA64_SGI_SN2 || IA64_GENERIC).

  What is the desired behavior?  Should generic kernels require these options?
Should we force these options on for platforms that support them, and therefore
make them non-user configurable?  Should we just turn them on by default, and 
allow users to disable them?

[1] 
|Age  	Author  	Annotate  	Comments
|8 months 	jbarnes@com[davidm] 	1.48 	ia64: force on appropriate generic options
|
|
|--- 1.47/arch/ia64/Kconfig	Sun May 30 21:34:28 2004
|+++ 1.48/arch/ia64/Kconfig	Sun May 30 21:34:28 2004
|@@ -57,6 +57,10 @@
| 
| config IA64_GENERIC
| 	bool "generic"
|+	select NUMA
|+	select ACPI_NUMA
|+	select VIRTUAL_MEM_MAP
|+	select DISCONTIGMEM
| 	---help---
| 	  This selects the system type of your hardware.  A "generic" kernel
| 	  will run on any supported IA-64 system.  However, if you configure

Re: IA64_GENERIC vs. NUMA/DISCONTIG/VIRTUAL_MEM_MAP

[Matthew Wilcox]

On Sun, May 30, 2004 at 10:48:43PM -0600, dann frazier wrote:
> hey,
>   It was requested that I turn on DISCONTIGMEM in my builds for Debian, in order to support
> Altix boxes.  This option is not currently selectable w/ a 2.6.6 "Generic" kernel, but
> it is with all other flavors.
> 
>   I dug around to see if this is intentional, and found evidence[1] that it is not.
> >From what I can grok from Documentation/kbuild/kconfig-language.txt, select will force
> these options off - maybe "depends on" is what was intended?

No, select forces these options on.  It's like Enhances: versus Suggests:
(if Enhances actually worked, which it doesn't).  The reason you can't
turn DISCONTIGMEM on with a generic kernel is because it's forced on.  I
suspect the bug submitter was smoking something good.

> | config IA64_GENERIC
> | 	bool "generic"
> |+	select NUMA
> |+	select ACPI_NUMA
> |+	select VIRTUAL_MEM_MAP
> |+	select DISCONTIGMEM

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain

Re: IA64_GENERIC vs. NUMA/DISCONTIG/VIRTUAL_MEM_MAP

[dann frazier]

On Mon, May 31, 2004 at 03:32:04PM +0100, Matthew Wilcox wrote:
> No, select forces these options on.  It's like Enhances: versus Suggests:
> (if Enhances actually worked, which it doesn't).  The reason you can't
> turn DISCONTIGMEM on with a generic kernel is because it's forced on.  I
> suspect the bug submitter was smoking something good.

I suspected that initially, but this is what confused me:
$ make oldconfig > /dev/null && grep IA64_GENERIC .config && grep CONFIG_NUMA .config
CONFIG_IA64_GENERIC=y
# CONFIG_NUMA is not set

However, I can set it by editing .config by hand, and oldconfig doesn't drop
it, so I'm good to go.

-- 
---------------------------
dann frazier
Hewlett-Packard
Linux and Open Source Lab
dannf@hp.com

Re: IA64_GENERIC vs. NUMA/DISCONTIG/VIRTUAL_MEM_MAP

[Andreas Schwab]

dann frazier <dannf@hp.com> writes:

> I suspected that initially, but this is what confused me:
> $ make oldconfig > /dev/null && grep IA64_GENERIC .config && grep CONFIG_NUMA .config
> CONFIG_IA64_GENERIC=y
> # CONFIG_NUMA is not set

Can't reproduce here.  Whenever I select IA64_GENERIC I also get NUMA=y,
even if I start with a .config that has NUMA=n.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: IA64_GENERIC vs. NUMA/DISCONTIG/VIRTUAL_MEM_MAP

[dann frazier]

On Mon, May 31, 2004 at 05:42:38PM +0200, Andreas Schwab wrote:
> dann frazier <dannf@hp.com> writes:
> 
> > I suspected that initially, but this is what confused me:
> > $ make oldconfig > /dev/null && grep IA64_GENERIC .config && grep CONFIG_NUMA .config
> > CONFIG_IA64_GENERIC=y
> > # CONFIG_NUMA is not set
> 
> Can't reproduce here.  Whenever I select IA64_GENERIC I also get NUMA=y,
> even if I start with a .config that has NUMA=n.

Seems the machine I was doing my builds on has crashed, and I'm out of the country
at the moment - I can send my config when I regain access.