Re: [bug] latest -git boot hang

Ingo Molnar
2008-10-11T14:34:29Z

* 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