Question about JDB in Fiasco

Adam Lackorzynski adam at
Sun Aug 30 23:19:26 CEST 2015


On Fri Aug 28, 2015 at 15:59:56 +0800, yang.wei9 at wrote:
> I have some questions about JDB in Fiasco.
> 1). Is there any latest manual about JDB? 
>     I can only find <Fiasco Kernel Debugger Manual>(
> which is written in 2008. 
>     This manual does not conform to the current fiasco 
> version(l4re-snapshot-2014092821)¡£

Yes, the manual is indeed outdated.

> 2). Does JDB support bt(dump backtrace)?
>     There are some descriptions about "bt" command in <Fiasco Kernel 
> Debugger Manual>. But I can not find it in current version.

The bt command as initially implemented used the gstabs debugging
information which has been long superseded by dwarf, being the superior
debugging info to use. Thus bt does not work anymore. Implementing it
based on dwarf is some considerable effort which has not (yet?) been
taken. Alternatively, we just look at the stack dump in the TCB view. Of
course it's not as nice as it could be but at least the colorization
helps quickly to identify what a value is very likely to be.

>     Does older version fiasco support it?
> 3). How can I get the older version fiasco code£¿

Switching back to gstabs debugging infos could be a way to get it
working again, if that still works tooling wise.

Adam                 adam at

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