L4/Fiasco kernel debugger (jdb) and step over command

Valery V. Sedletski _valerius at mail.ru
Wed Dec 27 16:33:16 CET 2017

On 27.12.2017 13:05, Matthias Lange wrote:
> Hi Valery,
>> On 26. Dec 2017, at 17:54, Valery V. Sedletski <_valerius at mail.ru> wrote:
>> Hi. I'm trying to debug my program with jdb. (I'm using the old L4/Fiasco / L4Env, not the current Fiasco.OC / L4Re). I enabled the permanent single step mode (with the S+ command) and a permanent show the Thread Control Block (with the t+ command) option. So, I was able to single-step with "g" command. Also, I found "jr" (go until return (ret or iret) is encountered) and "jb" (go until the next branch instruction, like jmp/call/int) commands, but they don't seem to work. When I enter them, I see only a single step to the next instruction. Are these two commands broken? How do I step over a "call"/"int" instruction?
> Fiasco/L4Env has been outdated for almost 10 years now and hasn’t been maintained since then. Sorry, but here we are unable to help you with your problem.
Yes, I know that  it's outdated now.
> Are there any reasons you chose Fiasco/L4Env over Fiasco.OC/L4Re?
My program is based on L4Env. I'm porting it to L4Re now. But first I 
need to fix some bug and then continue porting it to L4Re. I think, 
someone could remember some problems existed with L4/Fiasco kernel 
debugger. Also, Fiasco.OC debugger may be very similar, so I expected 
someone could help me. The problem is that I cannot find any commands 
similar to "step over" command. There are "jb" (continue to the next 
branch instruction) and "jr" (continue until next return instruction), 
but they don't seem to work. They just do a single stepping. Does still 
anybody remember how could I step over a "call" instruction? Maybe, in 
Fiasco.OC it's similar? Or, in Fiasco, it was completely broken in the end?
> Best,
> Matthias.
>> Thanks in advance,
>> valery
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