Re: [Qemu-devel] [PULL 14/49] scripts/kvm/kvm_stat: Improve debugfs access checking

[Paolo Bonzini]

On 02/02/2016 15:02, Christian Borntraeger wrote:
>> > -if not os.access('/sys/kernel/debug', os.F_OK):
>> > -    print 'Please enable CONFIG_DEBUG_FS in your kernel'
>> > +if not os.path.exists('/sys/kernel/debug'):
>> > +    sys.stderr.write('Please enable CONFIG_DEBUG_FS in your kernel.')
>> >      sys.exit(1)
>> > -if not os.access(PATH_DEBUGFS_KVM, os.F_OK):
>> > -    print "Please mount debugfs ('mount -t debugfs debugfs 
>> > /sys/kernel/debug')"
>> > -    print "and ensure the kvm modules are loaded"
>> > +if not os.path.exists(PATH_DEBUGFS_KVM):
>> > +    sys.stderr.write("Please make sure, that debugfs is mounted and "
>> > +                     "readable by the current user:\n"
>> > +                     "('mount -t debugfs debugfs /sys/kernel/debug')\n"
>> > +                     "Also ensure, that the kvm modules are loaded.\n")
>> > +    sys.exit(1)
>> > +if not os.path.exists(PATH_DEBUGFS_TRACING):
>> > +    sys.stderr.write("Please make {0} readable by the current user.\n"
>> > +                     .format(PATH_DEBUGFS_TRACING))
>> >      sys.exit(1)
> 
> Hmmm, this now bails out on kernels without CONFIG_TRACING. It could still 
> fall
> back to the normal kvm_stat values. What about just removing the last 
> sys.exit(1)
> and make this a warning that stays for a second or so?

Good idea.  Can you send a patch?

Paolo