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... Rob -- 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/
