When booting the same binary 32-bit kernel (via network), it boots sucessfully on PA7300 and above CPUs, while it fails with DTLB fault (trap #15) on my PA7100LC (PA11) machine. I've narrowed the problem down to the fixmap implementation. Here is the relevant part of the boot log (with some debug info included): Decompressing Linux... done. Booting the kernel. Linux version 5.15.0-rc6-32bit+ (deller@p100) (hppa-linux-gnu-gcc (GCC) 10.2.1 20200826 (Red Hat Cross 10.2.1-3), GNU ld version 2.34-2.fc33) #836 PREEMPT Wed Oct 27 20:01:14 CEST 2021 FP[0] enabled: Rev 1 Model 13 The 32-bit Kernel has started... ... TOC handler registered rcu: Hierarchical SRCU implementation. patch_multiple 101856d8 len = 4 set_fixmap phys = 0x185000 virt = 0xeffe000 parisc_tlb_flush_threshold = 0xffffffff FIXMAP_START = 0xeffe000 patch_multiple map at 0effe6d8 TRAP 15 0xeffe6d8 Backtrace: [<107bff04>] patch_text+0x28/0x40 [<107c0358>] arch_arm_kprobe+0x20/0x30 [<1022be4c>] arm_kprobe+0x4c/0x7c [<1022e1c0>] register_kprobe.part.0+0x150/0x16c [<1022e228>] register_kprobe+0x4c/0x60 [<1010858c>] 0x1010858c [<1010f178>] 0x1010f178 [<1017711c>] do_one_initcall+0x80/0x1ac [<10103378>] 0x10103378 [<107b98e4>] kernel_init+0x2c/0x154 [<1017401c>] ret_from_kernel_thread+0x1c/0x24 This is a log from the PA7300LC CPU: rcu: Hierarchical SRCU implementation. patch_multiple 101856d8 len = 4 set_fixmap phys = 0x185000 virt = 0xeffe000 parisc_tlb_flush_threshold = 0xffffffff FIXMAP_START = 0xeffe000 patch_multiple map at 0effe6d8 Kprobe smoke test: started patch_multiple 1021e800 len = 4 set_fixmap phys = 0x21e000 virt = 0xeffe000 parisc_tlb_flush_threshold = 0xffffffff FIXMAP_START = 0xeffe000 patch_multiple map at 0effe800 ... Again, this is exactly the same kernel booted on different machines. The only explanation I have for this is, that I believe the dtlb fault handler includes some assembler statements which are executed differently on PA7100 vs. PA7300 (and higher) CPUs. In the archives I found this old thread, which might be related: https://www.spinics.net/lists/linux-parisc/msg09391.html Anyway, here is the assembly: 10175738 <dtlb_miss_11>: 10175738: 23 3f a0 14 ldil L%abf000,r25 1017573c: 37 39 00 00 ldo 0(r25),r25 10175740: 0b 00 22 40 or,= r0,r24,r0 10175744: 03 20 08 b9 mfctl tr1,r25 10175748: 00 00 e4 a1 mfsp sr7,r1 1017574c: 0b 00 32 40 or,<> r0,r24,r0 10175750: 08 18 02 41 copy r24,r1 10175754: 08 20 22 40 or,= r0,r1,r0 10175758: 8b 01 31 72 cmpb,<>,n r1,r24,10176018 <dtlb_fault> 1017575c: d1 01 19 36 extrw,u r8,9,10,r1 10175760: d7 20 0c 14 depw r0,31,12,r25 10175764: 08 00 02 50 copy r0,r16 10175768: 0f 21 20 99 ldw,s r1(r25),r25 1017576c: c7 f9 c0 e2 bb,>=,n r25,1f,101757e4 <dtlb_check_alias_11> 10175770: d7 20 0c 1c depw r0,31,4,r25 10175774: 08 19 02 49 copy r25,r9 10175778: d7 29 09 08 depw,z r9,23,24,r25 1017577c: d1 01 1a 76 extrw,u r8,19,10,r1 10175780: d7 20 0c 14 depw r0,31,12,r25 10175784: 0b 21 06 99 shladd r1,2,r25,r25 10175788: 0f 20 10 90 ldw 0(r25),r16 1017578c: c6 d0 c0 a2 bb,>=,n r16,16,101757e4 <dtlb_check_alias_11> 10175790: 34 09 02 00 ldi 100,r9 10175794: 0a 09 02 41 or r9,r16,r1 10175798: 0a 09 32 00 and,<> r9,r16,r0 1017579c: 0f 21 12 80 stw r1,0(r25) 101757a0: d6 38 08 31 depw,z r24,30,15,r17 101757a4: d6 30 0e f9 depw r16,8,7,r17 101757a8: d2 00 3b 1f extrw,u,= r16,24,1,r0 101757ac: d6 22 1e 7f depwi 1,12,1,r17 101757b0: d2 00 3a 9f extrw,u,= r16,20,1,r0 101757b4: d6 2e 1e 9d depwi 7,11,3,r17 101757b8: d2 00 3b 9f extrw,u,= r16,28,1,r0 101757bc: d6 20 1e 9e depwi 0,11,2,r17 101757c0: d6 00 1c 14 depwi 0,31,12,r16 101757c4: d2 10 1b 07 extrw,u r16,24,25,r16 101757c8: 00 00 44 a9 mfsp sr1,r9 101757cc: 00 18 58 20 mtsp r24,sr1 101757d0: 05 10 50 40 idtlba r16,(sr1,r8) 101757d4: 05 11 50 00 idtlbp r17,(sr1,r8) 101757d8: 00 09 58 20 mtsp r9,sr1 101757dc: 00 00 0c a0 rfi,r 101757e0: 08 00 02 40 nop 101757e4 <dtlb_check_alias_11>: 101757e4: 8f 00 30 5a cmpib,<>,n 0,r24,10176018 <dtlb_fault> 101757e8: 20 20 01 e0 ldil L%f000000,r1 101757ec: 08 08 02 49 copy r8,r9 101757f0: d5 20 1c 09 depwi 0,31,23,r9 101757f4: 89 21 30 3a cmpb,<>,n r1,r9,10176018 <dtlb_fault> 101757f8: 02 60 08 a1 mfctl iir,r1 101757fc: d0 21 18 ba extrw,u r1,5,6,r1 10175800: 34 11 00 86 ldi 43,r17 10175804: 90 20 20 02 cmpiclr,= 1,r1,r0 10175808: 34 11 00 46 ldi 23,r17 1017580c: d6 31 0a f9 depw,z r17,8,7,r17 10175810: d1 00 39 3f extrw,u,= r8,9,1,r0 10175814: 08 17 12 50 or,tr r23,r0,r16 10175818: 08 1a 02 50 copy r26,r16 1017581c: 05 10 10 40 idtlba r16,(r8) 10175820: 05 11 10 00 idtlbp r17,(r8) 10175824: 00 00 0c a0 rfi,r 10175828: 08 00 02 40 nop Any idea what's going wrong or any suggestion I can try? Btw, I did tested older kernels too, but they all showed the same problem. Helge
