[oe] [PATCH] sanity.bbclass: Reading /proc/sys/vm/mmap_min_addr is not permitted with 2.6.33+ on host

[Phil Blundell]

On Sat, 2010-01-02 at 18:10 +0100, Martin Jansa wrote:
> * With 2.6.33-rc2-00252-ge9e5521 on my host I noticed that
>   "cat /proc/sys/vm/mmap_min_addr" returns now
>   "cat: /proc/sys/vm/mmap_min_addr: Operation not permitted"
>   Its probably becuse of
>   http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0e1a6ef2dea88101b056b6d9984f3325c5efced3
>   But I'm not sure if checking CAP_SYS_RAWIO even for reading this value
>   is intentional or just bug which should be fixed in kernel.
> 
> * This patch prints notice about need to check that value yourself (as
>   root) instead of failing with "ERROR: IO Error: [Errno 1] Operation
>   not permitted"
> 
> * Its not optimal, because this notice is shown every time you run
>   bitbake (even after checking/setting 0 to mmap_min_addr if you have
>   kernel not allowing to read it
> 

That does sound fairly unsatisfactory.  Printing a diagnostic on every
build, with no way for the user to suppress it, surely can't be the way
of the future.

If you can't tell whether mmap_min_addr is set correctly or not then it
would probably be better to not show the diagnostic at all.  Perhaps you
could investigate patching qemu to print a more meaningful message if it
actually encounters a mmap() failure of this kind.

p.