> -----Original Message----- > From: Andy Lutomirski [mailto:luto@xxxxxxxxxx] > Sent: Wednesday, September 27, 2017 3:49 PM > To: Darren Hart <dvhart@xxxxxxxxxxxxx>; Andy Shevchenko > <andy.shevchenko@xxxxxxxxx>; Andy Lutomirski <luto@xxxxxxxxxxxxxx> > Cc: Limonciello, Mario <Mario_Limonciello@xxxxxxxx>; Pali Rohár > <pali.rohar@xxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; Platform Driver <platform- > driver-x86@xxxxxxxxxxxxxxx>; quasisec@xxxxxxxxxx > Subject: Re: [PATCH 06/12] platform/x86: dell-wmi-smbios: Add a sysfs interface > for SMBIOS tokens > > On 09/27/2017 11:55 AM, Darren Hart wrote: > > On Wed, Sep 27, 2017 at 09:31:47PM +0300, Andy Shevchenko wrote: > >> On Wed, Sep 27, 2017 at 9:27 PM, <Mario.Limonciello@xxxxxxxx> wrote: > >> > >>>>>>> Darren, Andy, any comments? I'm not quite sure if such API is suitable > >>>>>>> for long term in kernel. > >>>>>> > >>>>>> I would try to avoid sysfs interfaces for some particular devices. > >>>>>> Besides we are creating a character device. Would it be suitable there? > >>>>> > >>>>> If the character device having 2 different ioctls for different needs is > >>>>> acceptable I'm happy to adjust the series to do this instead. > >>>> > >>>> One piece of feedback I had re the char device was to see if we could avoid the > >>>> need for the IOCTL altogether, I'd like to have that discussion before we add > >>>> another. > >>> > >>> My original design was sysfs files for everything but it was raised by several > folks > >>> that you run into the potential of two userspace processes stomping on each > >>> other's data when they run the ACPI call. That's why I need to have a mutex to > >>> protect and make sure that userspace calls get the right results. > >>> > >> > >>>>>>> Basically tokens are list of tuples <id, location, value> with > >>>>>>> possibility to active them, right? > >>>>>>> > >>>>> > >>>>> I didn't add a way to activate them through this, it was only for > >>>>> reading purpose. Activating them should be possible through the > >>>>> SMBIOS calling interface though. > >>>>> > >>>> > >>>> These are read-only as I understood it, and only with the right privileges. > >>>> Sysfs seemed appropriate for this to me. > >>> > >>> Andy S was against having this data as another sysfs file. From a userspace > >>> perspective I think it's simpler to just parse a sysfs file with read only static > >>> data as root. With the current ioctl based solution it requires userspace to run > >>> an ioctl to determine how many tokens exist, then allocate a chunk of memory > >>> big enough to hold all the token data and then run another ioctl to get all the > tokens. > >>> > >>> Andy S, given this change between v1 and v2 what do you feel is better? > >> > >> I have no strong opinion on this. That's why I recommended to listen to Andy L. > > > > +Andy Lutomirski > > > > Andy L, any preference on your part regarding exporting these tokens via sysfs > > or through an additional IOCTL in the chardev? > > > > Not really. If this is indeed static data that is potentially useful > for scripts and such, than sysfs is kind of nice. OK thanks. I'll switch back to sysfs for v3.
