RE: A clash happened in kernel by glibc-2.33

RE: A clash happened in kernel by glibc-2.33

[Zeng, MingwangX]

Hi, alpha
	I tried kernel versions 4.9.257, 4.9.258, and they all crashed.
	I don't use the option --enable-kernel, as we update kernel more frequently than glibc .
	Is this option --enable-kernel=4.9.255  compatible with versions after 4.9.255?

BR,
Mingwang

-----Original Message-----
From: Carlos O'Donell <carlos@redhat.com> 
Sent: Wednesday, June 30, 2021 10:29 PM
To: Zeng, MingwangX <mingwangx.zeng@intel.com>; libc-maintainers@gnu.org
Subject: Re: A clash happened in kernel by glibc-2.33

On 6/30/21 2:29 AM, Zeng, MingwangX wrote:
> Hi, Glibc maintainers

Zeng,

Please send this to libc-alpha@sourceware.org, and we'll have a development discussion there?

Please provide the exact value of --enable-kernel that was used to trigger this defect and why you selected that given kernel version.

No default selection will trigger this because we set the Z component of the version to 0 in the defaults.
 
> A clash happened in kernel by glibc-2.33.
> 
>                Scene:
>                when kernel mini version lager then 255, glibc could cause the clash.
> 
> FATAL: kernel too old
> Kernel panic - not syncing: Attempted to kill init! 
> exitcode=0x00007f00
> 
> Reason:
>           sysdeps/unix/sysv/linux/dl-sysdep.c
>           line:
>    110    while ((*cp >= '0') && (*cp <= '9'))
>    111      {
>    112        unsigned int here = *cp++ - '0';
>    113
>    114        while ((*cp >= '0') && (*cp <= '9'))
>    115          {
>    116            here *= 10;
>    117            here += *cp++ - '0';
>    118          }
>    119
>    120        ++parts;
>    121        version <<= 8;
>    122        version | = here; // root case.
> 
>                               Such as Kernel version is 4.9.256 , it will be : version |= 256 ;
>                               Version == 4.9.0
> 
>                Would you please provide me with a temporary patch, think you very much!
> 
> BR,
> Mingwang.
> 
> 
> 


--
Cheers,
Carlos.

Re: A clash happened in kernel by glibc-2.33

[Florian Weimer]

* MingwangX via Libc-alpha Zeng:

> 	Is this option --enable-kernel=4.9.255  compatible with versions after 4.9.255?

You should use --enable-kernel=4.9.0, it will avoid this issue.  Using a
higher number than 0 in the last component does not enable any
additional glibc optimizations.  Or you could drop this configure option
entirely, it is not needed for correct operation.

Thanks,
Florian