trap (GPF) when starting l4linux -- resolved!
adam at os.inf.tu-dresden.de
Thu Sep 25 19:45:21 CEST 2008
On Wed Sep 24, 2008 at 14:09:10 +1300, valerius wrote:
> I spent a night reconfiguring Fiasco and L4Linux and reading the Mailing list
> archive. And it appears that l4linux itself was configured correctly. But I
> encountered a troubles with 'Mysterious double fault' when using QEMU that
> could be overcome if disable 'Assembler IPC shortcut' option in Fiasco
> configuration. Also I found that options in loader config file have
> significant order of precedence. They should appear in the following order:
> If all_sects_writable appears before allow_cli then loader says that l4linux
> task is not allowed to do any I/O. It is really strange and non-obvious.
> Also, some diversity in options order may lead to unresolved page faults and
> GPFs like the GPF which I was asking for.
> Someone can say it is very trivial but I spent a night to figure out the way
> it works.
> I just wanted to point these non-obvious moments to novices. (and, maybe,
> developers of loader server -- what if to make these options order to be
> non-significant? It could make loader behaviour more predictable.)
Thanks for describing your findings!
I don't understand why the order plays a role, looking at the code.
Those options are just task flags which are parsed and toggle some bits
in a flag word. I don't see how order could be important.
And yes, GPFs should not happen, I second.
Adam adam at os.inf.tu-dresden.de
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