On Fri, Sep 21, 2018 at 03:00:19AM +0200, David Lamparter wrote: > On Thu, Sep 20, 2018 at 07:31:33PM -0500, Scott Wood wrote: > > Do you have a JTAG that can be used to find out where it's hanging? If > > not, I can try to get early debug working (needs an early IOMMU mapping).
s/IOMMU mapping/MMU mapping for MMIO/ :-P > I only have JTAG tools for ARM chips available; hardware wise I could > probably solder up an adapter but software wise I have absoutely no clue > how to fire up a session on anything PPC... I'm a novice openocd user, > that's it. > > > York, can you try booting the latest kernel on p4080ds? > > d9e1831a42 has been around for quite some time, 4.4 already has it. I > was a bit surprised noone has run into this, but then again P4080 is not > exactly the most recent/interesting hardware. I don't suppose you're running a relocatable kernel at a non-zero address, and/or are running in an environment that sets HID0[EN_L2MMU_MHD] (neither standard U-boot nor Linux sets this bit, though they probably should)? On 32-bit, we're already running in an AS1 trampoline when loadcam_multi() is called, but loadcam_multi() sets up its own. This happens to not be catastrophic in standard scenarios, but it does add a duplicate TLB entry, and we return to AS0 sooner than expected. I think your patch, plus ifdefs to make the change 32-bit only, is the appropriate fix. I also got an earlier udbg for e500 working (and happened to decide to test it with a relocatable kernel); I'll send that out once I've cleaned it up (or sooner with the extra TLB dumping included if the above doesn't explain why you're hitting this bug). -Scott
