Hi community,
When I try KGDB (with kgdboc), and 'echo g > /proc/sysrq-trigger' to
trigger kgdb, I got below error:
------
CPU 0 Unable to handle kernel paging request at virtual address
00000000, epc == 00000000, ra == 80223f38
KGDB: re-enter exception: ALL breakpoints killed
(This causes a kernel panic)
------
My setup is:
- Atheros AR9331 chip, which is MIPS32 24kc
- OpenWRT tag 15.05
- Linux kernel v3.18.29
The issue seems with inline assembly?
void arch_kgdb_breakpoint(void)
{
__asm__ __volatile__(
".globl breakinst\n\t"
".set\tnoreorder\n\t"
"nop\n"
"breakinst:\tbreak\n\t"
"nop\n\t"
".set\treorder");
}
There seems a fundamental question about OpenWRT linux kernel?
- In file OpenWRT file target/linux/ar71xx/Makefile, there is CPU_TYPE=34kc
- Atheros AR9331 datasheet says it is 24kc (rather than 34kc)
- With CPU_TYPE=34kc, it uses gcc options "-mips32r2 -mtune=34kc"
Quotes from mips website: https://www.imgtec.com/mips/classic/
------
MIPS32 34Kc/f
The MIPS32 34K is a 9-stage pipeline multi-threaded processor core with
support for up to two Virtual Processing Elements (VPE) and nine Thread
Context (TC)s per VPE.
MIPS32 24K
The MIPS32 24K is a 8-stage pipeline processor core that implements the
MIPS32 Release 2 Architecture,
------
Does KGDB work on MIPS32 24kc (Atheros AR9331 chip)? Thanks.
Xuebing Wang
