Re: [Outreachy kernel] Re: [Y2038] [PATCH v2] Staging: fbtbt: Replace timespec with ktime_t

[Arnd Bergmann <arnd@arndb.de>]

On Monday 05 October 2015 10:47:05 Sudip Mukherjee wrote:
> On Sun, Oct 04, 2015 at 09:34:40PM +0200, Arnd Bergmann wrote:
> > On Saturday 03 October 2015 21:15:46 Ksenija Stanojević wrote:
> > Two possible explanations why you don't get it:
> > 
> > - your .config file got changed back to CONFIG_64BIT being enabled
> > - you don't have CONFIG_FB_TFT enabled in this build.
> 
> After modifying manually .config file use make oldconfig and then make
> prepare.
> I think i missed the beginning of the thread. Are you saying that fbtft
> build fails on 32 bit arch?

Ksenija's patch from last week causes this build regression, but it is not
merged yet. This is my original comment:

| > -             ts_duration = timespec_sub(ts_end, ts_start);
| > -             duration_ms = (ts_duration.tv_sec * 1000) + ((ts_duration.tv_nsec / 1000000) % 1000);
| > -             duration_us = (ts_duration.tv_nsec / 1000) % 1000;
| > -             throughput = duration_ms * 1000 + duration_us;
| > +             throughput = ktime_us_delta(ts_end, ts_start);
| >               throughput = throughput ? (len * 1000) / throughput : 0;
| >               throughput = throughput * 1000 / 1024;
| 
| As mentioned above, throughput is a 64-bit 'long long', so the last line
| of the context will result in a 64-bit division, which is not allowed in
| 32-bit kernels.

	Arnd