> On Jan 28, 2015, at 11:57 PM, Rob Herring <robherri...@gmail.com> wrote: > > On Wed, Jan 28, 2015 at 8:33 AM, Nicolas Pitre <n...@fluxnic.net> wrote: >> On Wed, 28 Jan 2015, Pali Rohár wrote: >> >>> On Wednesday 28 January 2015 01:50:33 Tony Lindgren wrote: >>>> On omaps, the bootrom passes the bootreason in r1 to the >>>> bootloader that can do whatever it wants with it. We could >>>> maybe pass it in the kernel cmdline to the watchdog driver >>>> for user space? >>>> >>> >>> Not truth for N900. Bootreason depends on PRM_RSTST omap >>> register, state of vbat charger pins, time how long was power key >>> pressed, R&D data stored in CAL partition and other undocumented >>> registers for omap HS devices. I already tried to implement at >>> least some subset of it in userspace (or kernel), but it is >>> impossible because NOLO bootloader clear status of PRM_RSTST >>> register. >>> >>> There is also copy of PRM_RSTST register stored at address >>> 0x4020FFB8 (tracing data) but that address is rewritten (probably >>> by kernel), so we really cannot implement reading bootreason in >>> kernel. >>> >>> But in early stage in uboot it is possible to read 0x4020FFB8 >>> address and get some part of bootreason. But still PRM_RSTST is >>> not enough! >>> >>> I would be happy if DT kernel can export /proc/atags file with >>> ATAGs passed by bootloader. It would be enough for me. In >>> userspace I can parse content and do what is needed. >> >> What about defining a DT boot reason property instead? >> Maybe it already exists? If not, it's something that could certainly be >> generically used on other platforms too. > > I'm fine with that, but we just need to have a standard kernel > userspace interface in addition to something like > /proc/device-tree/bootreason. Perhaps this can be the default > implementation for the watchdog dev. Someday when we decide DT is crap > and have a new boot interface, we'll have people relying on > /proc/device-tree. I hope to be retired when that happens…
but if we try to do this generic, where will you store the boot mode I mean where the SoC boot from useful to for the Userspace to known where is the bootloader in case of multi boot mode Best Regards, J. > > Rob > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-ker...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
