Re: [bug] latest -git boot hang

[Ingo Molnar <mingo@elte.hu>]

* Jens Axboe <jens.axboe@oracle.com> wrote:

> On Sat, Oct 11 2008, Ingo Molnar wrote:
> > 
> > * Tejun Heo <tj@kernel.org> wrote:
> > 
> > > > It does sound like perhaps the option should be hidden more, if it's 
> > > > really only reasonably enabled for some very specialized distro 
> > > > debuggers, not normal kernel people.
> > > 
> > > Yeap, if fedora didn't work, I think it should be hidden.  Do we 
> > > already have place to hide things like this?
> > 
> > in my local testing i'm using simple annotations like the one attached 
> > further below. Any objections against sending my BROKEN_BOOT_ALLOWED kit 
> > upstream, and merge my annotations for various kernel features that 
> > break a generic distro bootup?
> > 
> > Right now i have about 40 such annotations for -tip testing:
> > 
> >   fs/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   fs/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   security/selinux/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   security/smack/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   security/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/net/appletalk/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/net/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/media/video/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/scsi/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/watchdog/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/watchdog/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/ide/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/i2c/busses/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/block/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/console/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/video/console/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/mtd/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   drivers/isdn/icn/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   lib/Kconfig.kgdb:	depends on BROKEN_BOOT_ALLOWED
> >   lib/Kconfig.debug:	depends on BROKEN_BOOT_ALLOWED
> >   lib/Kconfig.debug:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig.debug:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	# depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig:	depends on BROKEN_BOOT_ALLOWED
> >   arch/x86/Kconfig.cpu:	depends on BROKEN_BOOT_ALLOWED
> > 
> > and note the stark contrast to CONFIG_BROKEN - sometimes a given 
> > functionality is really not meant to be enabled on a generic system.
> > 
> > 	Ingo
> > 
> > ---------------->
> > Subject: qa: no ext devt
> > From: Ingo Molnar <mingo@elte.hu>
> > Date: Fri Oct 10 22:54:57 CEST 2008
> > 
> > Signed-off-by: Ingo Molnar <mingo@elte.hu>
> > ---
> >  lib/Kconfig.debug |    2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > Index: linux/lib/Kconfig.debug
> > ===================================================================
> > --- linux.orig/lib/Kconfig.debug
> > +++ linux/lib/Kconfig.debug
> > @@ -670,6 +670,8 @@ config DEBUG_BLOCK_EXT_DEVT
> >          bool "Force extended block device numbers and spread them"
> >  	depends on DEBUG_KERNEL
> >  	depends on BLOCK
> > +	depends on BROKEN_BOOT_ALLOWED
> > +	select BROKEN_BOOT
> >  	default n
> >  	help
> >  	  Conventionally, block device numbers are allocated from
> 
> What is BROKEN_BOOT_ALLOWED? Honestly, I'd prefer to just put an extra 
> 2-3 line paragraph in the help entry, saying that it's quite possible 
> that current distros wont boot with this testing code enabled. Since 
> it default to 'n', people should read the entry before turning it on 
> anyway.

well, the extra BROKEN_BOOT_ALLOWED helps my automated test-setup to 
decide whether a .config that it's testing (either sent by a reporter or 
generated randomly) can be booted.

If CONFIG_BROKEN_BOOT_ALLOWED=y, then i allow config options that can 
break the bootup. In that case, and _if_ such a possibly-boot-breaking 
config option is enabled, CONFIG_BROKEN_BOOT is set - which my scripts 
detect.

This gives the test harness the highest flexibility and annotates those 
kernel features / drivers which can result in a (possibly) broken 
bootup. The scripts cannot read help entries.

	Ingo