Re: [bug] latest -git boot hang

[Jens Axboe <jens.axboe@oracle.com>]

On Sat, Oct 11 2008, Ingo Molnar wrote:
> 
> * 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.

OK, makes sense to me then, thanks. I was afraid it was some user
exposed parameter, in which case it sounded... interesting :-)

For users, we just need to expand the help entry a bit.

-- 
Jens Axboe