On Mar 7, 2016 5:07 PM, "Roger Koehler" <[email protected]> wrote:
>
> > On Mar 7, 2016 4:50 PM, "Ken Moffat" <[email protected]> wrote:
> > >
> > > On Mon, Mar 07, 2016 at 04:22:22PM -0700, Roger Koehler wrote:
> > > > > You need to include the driver required for your rtc in the
kernel config.
> > > > > Clearly that is missing.
> > > > >
> > > > > Find out which driver your old kernel is using for the rtc
driver. Clearly
> > > > > a newer kernel version wouldn't mess up the rtc layout so much
that a make
> > > > > oldconfig wouldn't work from the previous kernel config.
> > > >
> > > > cat /sys/class/rtc/rtc0/dev
> > > > 254:0
> > > >
> > > > cat /sys/class/rtc/rtc0/name
> > > > rtc_cmos
> > > >
> > > > Same for both. I really believe they changed the rtc driver code.
> > >
> > > I can vaguely remember that something changed in the rtc area in the
> > > last couple of years, but there is nothing in my notes - I guess
> > > that I just fixed up my .config, probably after noticing a change on
> > > an -rc kernel.
> > >
> > > This is what I have on my SandyBridge, I suspect my other machines
> > > are similar, so let's start with this:
> > >
> > > CONFIG_RTC_LIB=y
> > > CONFIG_RTC_CLASS=y
> > > CONFIG_RTC_HCTOSYS=y
> > > CONFIG_RTC_HCTOSYS_DEVICE="rtc0"
> > > CONFIG_RTC_SYSTOHC=y
> > > CONFIG_RTC_SYSTOHC_DEVICE="rtc0"
> > >
> > > # CONFIG_RTC_DEBUG is not set
> > >
> > > #
> > > # RTC interfaces
> > > #
> > > CONFIG_RTC_INTF_SYSFS=y
> > > CONFIG_RTC_INTF_PROC=y
> > > CONFIG_RTC_INTF_DEV=y
> > > # CONFIG_RTC_INTF_DEV_UIE_EMUL is not set
> > > # CONFIG_RTC_DRV_TEST is not set
> > >
> > >  [ ... ]
> > >
> > > #
> > > # Platform RTC drivers
> > > #
> > > CONFIG_RTC_DRV_CMOS=y
> > >
> > > Does any of that differ from what you have ?
> >
> > Just SYSTOHC because I don't want the system to write over the rtc
automatically.
>
> Also, within chroot:
>
> # hwclock -r
> Mon 07 Mar 2016 05:01:55 PM MST  .077352 seconds
>
> But, after booting with the new kernel:
>
> # hwclock -r
> hwclock: ioctl(RTC_RD_TIME) to /dev/rtc to read the time failed: Invalid
argument

p.s. I am using LFS 7.6 with Linux 3.16.7 as host. Same kernel config as
starting point. I just rebuilt it to be sure.
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