On Fri, Aug 16, 2019 at 2:14 PM Daniel Drake <drake@xxxxxxxxxxxx> wrote: > Anyway, the system freeze occurs in parse_setup_data(), specifically: > > data = early_memremap(pa_data, sizeof(*data)); > data_len = data->len + sizeof(struct setup_data); > > Dereferencing data->len causes the system to hang. I presume it > triggers an exception handler due to some kind of invalid memory > access. > > By returning early in that function, boot continues basically fine. So > I could then log the details: pa_data has value 0x892bb018 and > early_memremap returns address 0xffffffffff200018. Accessing just a > single byte at that address causes the system hang. I noticed a complaint about NX in the logs, right where it does the early_memremap of this data (which is now at address 0x893c0018): Notice: NX (Execute Disable) protection missing in CPU! e820: update [mem 0x893c0018-0x893cec57] usable ==> usable e820: update [mem 0x893c0018-0x893cec57] usable ==> usable e820: update [mem 0x893b3018-0x893bf057] usable ==> usable e820: update [mem 0x893b3018-0x893bf057] usable ==> usable Indeed, in the BIOS setup menu, "NX Mode" was Disabled. Setting it to Enabled avoids the hang and Linux boots as normal. Weird! Daniel
