Hi Martin,
Thanks, that was very informative and made things a lot clearer to me - it
should keep me going for the next few weeks!
Enjoy your holiday,
CheersNick
>
> Hi Nick,
>
> I'm pleased to hear that you've found the time to proceed.
>
> ...
>
> You're right concerning the directory 'src/platform'. Due to the fact
> that 'base-hw' solely targets ARM systems for now, the separation of
> generic and platform specific code is not proven very well. I've
> annotated this issue, thank you!
>
> Moreover i'm not sure if i've understood you right regarding
> 'mode_transition.s'. The file does not really handle or control any type
> of exception. It's purpose is on the one hand to only catch exceptions,
> wich occur in userland, save the interrupted user execution-state and
> exception information, and get back to the kernel enviroment to re-run
> 'kernel()'. On the other hand it offers also the opposite direction,
> that is resuming a given user execution-context in userland once
> 'kernel()' returns. This way the handling of the concrete exception,
> whether it is an interrupt, a page fault or a syscall, resides
> completely in 'kernel()'.
>
> If you were looking for the resolution of page faults, even 'kernel()'
> is not the final destination. When kernel detects the presence of a page
> fault, the function 'handle_pagefault()' only checks if the fault was
> caused by a translation miss. If this is the case a pager might resolve
> the problem by expanding the according page table. Thus kernel composes
> an appropriate IPC message to the pager that is identified by the thread
> object of the faulter. The pager normally is a thread in Genodes 'core'
> process, wich itself asks the so called "Region Manager"
> of the faulter for a region mapping that covers the fault. If a mapping
> is found the pager modifies the page table accordingly. The only process
> that doesn't need pagers is 'core'. Because 'core' is the first process
> in Genode, gets initialized by 'kernel()' and must be trusted anyway,
> its page table gets filled with static 1:1 translations initially by
> kernel. Once this is done, kernel itself joins this process, so userland
> threads in 'core' and the kernel "thread" share the same address space.
>
> Long story short, the configuration of virtual/effective addresses
> depends, except of 'core' on the region managers, wich themselves are
> instructed through the RM-sessions
> (base/include/rm-session/rm_session.h) they provide to their RPC-clients.
>
> I hope this gives you a rough picture of Genodes virtual-address
> management, even it is a somewhat far-reaching explanation.
>
> Cheers,
> Martin
>
> On 08/08/2012 06:24 PM, Nick Betteridge wrote:
> > Hi Martin,
> >
> > ...
> >
> > I have been slowly reading through your arm assembler, trying to
> > understand how genode works.
> >
> > Just one thing - you have partitioned both arm processors and platforms
> > into named directories, except for base_hw/src/platform, which contains
> > arm assembler. Do you intend to refactor this into something like
> > base_hw/src/platform/arm?
> >
> > Just one more thing, am I right in thinking
> >
> > 'base-hw/src/core/arm_v7a/mode_transition.s'
> >
> > is just for interrupt control? I can't find anything for configuring
> > virtual/effective addresses - perhaps this is done in 'c' (I haven't
> > read the c yet) - in openrisc this is handled in the supervisor mode.
> >
> > Cheers
> > Nick
> >
> >
> >
> >
>
>
>
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> Genode-main mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/genode-main
------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and
threat landscape has changed and how IT managers can respond. Discussions
will include endpoint security, mobile security and the latest in malware
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
_______________________________________________
Genode-main mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/genode-main
