[yocto] [PATCH][linux-yocto] mount_root: clarify error messages for when no rootfs found (V2)
Bruce Ashfield
bruce.ashfield at windriver.com
Wed Nov 16 08:46:26 PST 2011
On 11-11-16 11:00 AM, Darren Hart wrote:
>
>
> On 11/16/2011 07:51 AM, Bruce Ashfield wrote:
>> On 11-11-16 10:45 AM, Darren Hart wrote:
>>>
>>>
>>> On 11/15/2011 09:36 PM, Bruce Ashfield wrote:
>>>> On 11-11-15 3:19 PM, Darren Hart wrote:
>>>>> The following is a modified version the patch at:
>>>>
>>>> Works for me as well, I'll update the variant in the yocto kernel
>>>> trees, while we wait to see if anyone upstream has any interest.
>>>
>>> I we can't get it upstream, I'd argue we drop this. As Paul said, it is
>>> cosmetic. When people see this error, the only place they'll find help
>>
>> I have no plans to drop this. It's a value add, and simply
>> because not everyone wants it, doesn't mean we let it go.
>>
>> We can carry it and try again if it doesn't make it upstream.
>>
>>> is here on the yocto list. They should be able to debug the kernel with
>>> all the Linux Kernel resources out there. Having custom kernel messages
>>> for Yocto prevents that.
>>
>> I disagree.
>
> With which part? That they should be able to use all the available
> resources? Or that custom kernel messages restrict where they can get
> help? I don't see how you can really argue against either of those...
Sorry for the short reply, I was being pulled away and couldn't
elaborate.
I don't see the two issues as being tied together or at least
not signifcantly. If two people are debugging a kernel issue, it is
incumbent that they know the trees they are using and to ensure that
they are at least somewhat in sync. The changes aren't hidden in any
way, so it's easy to know what is in play.
It's no different than using a arch/vendor tree versus mainline
or linux-next, or even two different mainline trees where one has
a changed strings. A grep or search will fail, and at that point
we sync on the tree versions and make sure they match.
There's plenty of other bigger issues that a few different
messages coming out of the kernel that can prevent people from
using resources. So I'm not arguing that it isn't a factor, I'm
just saying that it (a custom message) isn't a significant one.
Obviously we want the patch to be upstream, that's a baseline
goal for any change and I understand frustration and losing some
time during debug. But that particular message has been proven
to save lots of time in many other situations, so I wouldn't shoot
myself in the foot by dropping it based solely on it not being
upstream.
I'd modify it to meet comments, make it optional, prepend
[yocto], dropping it would be last resort.
I'm heading AFK again, but will be back later today.
Cheers,
Bruce
>
> --
> Darren
>
>>
>> Bruce
>>
>>>
>>> --
>>> Darren
>>>
>>>>
>>>> Bruce
>>>>
>>>>>
>>>>> meta/cfg/kernel-cache/patches/boot/mount_root-clarify-error-messages-for-when-no-rootfs.patch
>>>>>
>>>>> in the linux-yocto-3.0 git repository. This version adds KERN_EMERG
>>>>> so that even using loglevel=1 at boot, the end user will see:
>>>>>
>>>>> [ 0.217462] VFS: Unable to mount root fs on unknown-block(8,2)
>>>>> [ 0.223457] User configuration error - no valid root filesystem found
>>>>> [ 0.230057] Kernel panic - not syncing: Invalid configuration from end user preg
>>>>> [ 0.238992] Pid: 1, comm: swapper Not tainted 3.0.4-yocto-standard+ #2
>>>>> [ 0.245691] Call Trace:
>>>>> [ 0.248218] [<c04eddbc>] ? 0xc04eddbc
>>>>> [ 0.252071] [<c05549ad>] ? 0xc05549ad
>>>>> [ 0.255928] [<c05549fa>] ? 0xc05549fa
>>>>> [ 0.259790] [<c0554623>] ? 0xc0554623
>>>>> [ 0.263650] [<c0554b1c>] ? 0xc0554b1c
>>>>> [ 0.267497] [<c055472a>] ? 0xc055472a
>>>>> [ 0.271344] [<c04f0df6>] ? 0xc04f0df6
>>>>>
>>>>> Instead of just:
>>>>>
>>>>> [ 0.230057] Kernel panic - not syncing: Invalid configuration from end user preg
>>>>> ...
>>>>>
>>>>> Which is arguably no better than what this patch originally attempted to address.
>>>>>
>>>>> Paul, has this patch been sent upstream for inclusion? I don't see it in Linus' tree.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Darren
>>>>>
>>>>> ----------------------
>>>>>
>>>>> To an end user who doesn't really know linux that well, a
>>>>> message like:
>>>>>
>>>>> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
>>>>>
>>>>> may just look like cryptic computer speak indicating some
>>>>> deep and complex problem, instead of the reality that they
>>>>> have a simple local configuration problem. Ideally it would
>>>>> be nice to not use the misleading "panic" at all, but since
>>>>> various panic notifiers are historically expecting to be
>>>>> called when there is no valid rootfs, we can't change that.
>>>>>
>>>>> So instead, this tries to make it 100% clear to folks of
>>>>> any background that it is an end user configuration issue.
>>>>>
>>>>> V2: Use KERN_EMERG so the printk context isn't lost when using loglevel
>>>>>
>>>>> Signed-off-by: Paul Gortmaker<paul.gortmaker at windriver.com>
>>>>> Signed-off-by: Darren Hart<dvhart at linux.intel.com>
>>>>> ---
>>>>> init/do_mounts.c | 8 ++++++--
>>>>> 1 files changed, 6 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/init/do_mounts.c b/init/do_mounts.c
>>>>> index bb008d0..d24b8c7 100644
>>>>> --- a/init/do_mounts.c
>>>>> +++ b/init/do_mounts.c
>>>>> @@ -270,7 +270,9 @@ retry:
>>>>> printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
>>>>> "explicit textual name for \"root=\" boot option.\n");
>>>>> #endif
>>>>> - panic("VFS: Unable to mount root fs on %s", b);
>>>>> + printk(KERN_EMERG "VFS: Unable to mount root fs on %s\n", b);
>>>>> + printk(KERN_EMERG "User configuration error - no valid root filesystem found\n");
>>>>> + panic("Invalid configuration from end user prevents continuing");
>>>>> }
>>>>>
>>>>> printk("List of all partitions:\n");
>>>>> @@ -282,7 +284,9 @@ retry:
>>>>> #ifdef CONFIG_BLOCK
>>>>> __bdevname(ROOT_DEV, b);
>>>>> #endif
>>>>> - panic("VFS: Unable to mount root fs on %s", b);
>>>>> + printk(KERN_EMERG "VFS: Unable to mount root fs on %s\n", b);
>>>>> + printk(KERN_EMERG "User configuration error - no valid root filesystem found\n");
>>>>> + panic("Invalid configuration from end user prevents continuing");
>>>>> out:
>>>>> putname(fs_names);
>>>>> }
>>>>
>>>
>>
>
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