Hi Zoltan! On 10/26/21 00:40, BALATON Zoltan wrote: > On Tue, 26 Oct 2021, John Paul Adrian Glaubitz wrote: >> Hi Zoltan! >> >> On 10/23/21 15:22, BALATON Zoltan wrote: >>>> You either need to strip the kernel with "strip vmlinux" or use the image >>>> from arch/sh/ >>>> boot/zImage. >>> >>> I've actually used that kernel but looked at the wrong uncompressed size, >>> it's indeed just >>> 9.2MB when stripped so that should work. I was trying to debug further and >>> found two problems: >>> >>> Commit abb0cd93494 (accel/tcg: Split out log_cpu_exec) seems to have broken >>> -singlestep -d in_asm,cpu >>> output with sh after a delay slot. Since that commit I get: >>> (...) >>> This seems to take a wrong turn at the delayed branch and somehow ends up >>> at 0x8c800964 instead of >>> 0x8c801528 but I'm not sure where to look firther why. I'm cc-ing Richard >>> for both the -d cpu and >>> this hoping he has some more insight. >> >> Shall we open a bug report? > > Well, we don't know yet what to put in the bug report apart from there is > some bug somewhere. That's > not too useful. I now understand that the -d output is not showing already > translated TBs (I knew this > but most of the time with -singlestep it gives good results anyway) but here > it runs the loops without > further output then we only see the first loop iteration and the end result. > So the problem is not that > it goes to 0x8c800964 as I think that's part of the loop for decompressing > the kernel but it seems > something is overwriting 0x8c800964 while it still expects to run code from > there but I don't know what > and why. One way to find could be to disassemble the kernel code and compare > that with the -d output and > check every instruction manually but that takes a lot of time or if you have > a cross debugger you could > try attaching that to QEMU and try to debug it that way but I don't have that > either. Any other idea how > to find out what is happening?
Robert Święcki (CC'ed) found out that disabling tracing support makes Debian's kernel bootable [1]. Not sure if this is a kernel bug or a QEMU bug then. Does QEMU have any support for kernel tracing? Adrian > [1] https://marc.info/?l=linux-sh&m=164193147916418&w=2 -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer - glaub...@debian.org `. `' Freie Universitaet Berlin - glaub...@physik.fu-berlin.de `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
