IRC channel logs

<damo22>interesting, -smp 1 has same thread_select page fault

<damo22>maybe i changed something that should not have been changed

<damo22>youpi: start acpi: acpi Kernel Debug trap trap, eip 0xc10565b9

<damo22>Stopped at db_load_context+0x49: movl %edi,%dr0

<damo22>db_load_context(f484b000,f484b0bc,10,c1008d68,c11d8e44)+0x49

<damo22>switch_ktss(f484b000,2000,f4843e80,c1008f75,0)+0x82

<damo22>stack_handoff(f484c000,f482fa88,0,c10318e8,f4843ec8)+0x159

<damo22>..

<damo22>is the debugger itself getting in the waY?

<damo22>im getting a deadlock near start of rumpdisk process but cpus are all idle and no interrupts are happening

<damo22>maybe CPU_NUMBER turned off interrupts and nothing enabled them

<damo22>youpi: how do i protect CPU_NUMBER from being interrupted?

<youpi>damo22: cli

<youpi>but that should already be the case, normally

<youpi>as in context switching code etc. most probably already run at high spl

<youpi>perhaps add in CPU_NUMBER some code that checks the interrupt flag in eflags, and ud2 if it's wrong, so you can catch what codepath wouldn't already have interrupts disabled

<youpi>that being said, why would interrupts be a problem?

<damo22>when i add "cli" at the start of CPU_NUMBER, the machine almost boots but gets stuck waiting for an interrupt

<damo22>all cpus are idle sitting there doing nothing

<damo22>and timer interrupts are not happening

<youpi>did you add sti?

<damo22>no

<youpi>actually better: save eflags values, and restore it

<youpi>then don't be surprised that interrupts are disabled :)

<youpi>if you disable them with cli but don't enable them back with sti

<damo22>ok

<youpi>but you need to support nesting

<youpi>thus save flags and restore them

<youpi>it'd be really useful that you read about operating systems details

<damo22>ok

<youpi>such as "The Linux kernel"

<youpi>(bovet & cesati)

<youpi>such kind of tricks are well explained there

<damo22>i understand but dont know how to do it in asm

<damo22>i will grep for it

<youpi>grep for pushf

<damo22>pushfl ; cli; DO STUFF; popfl ?

<youpi>that's the idea yes

<damo22>its crashing at db_load_context

<damo22>in switch_ktss

<damo22>trap trap

<damo22>it booted but slowly to root shell

<civodul>howdy!

<civodul>does "watch/T" work as expected in kdb?

<civodul>i'm wondering if it's really watching

<Pellescours>almost boot with rump (without-linux-group) but trap just after boot process finished (around DHCP step)

<Pellescours>but with smp but 1 cpu, no trap, I will investigate

<Pellescours>ah it just trapped but after (at the time to getting me login console)

IRC channel logs

2022-10-12.log