Platform Initialization Problem

[Martin Stein]

Hi Praveen,
Stefan isn't online these days.
'Genode::map_local()' uses the
'Kernel::core_pd()->platform_pd()->page_slab()' as backing store. This
allocator is of the type 'Genode::Page_slab' as defined in
'base-hw/src/core/include/page_slab.h'. The class contains a member
'Slab_block _initial_sb' which is used for the first couple of
allocations (especially for the allocation of the second slab block).
Furthermore the page slab of the core PD is created via the
'unmanaged_singleton' utility in 'base-hw/src/core/kernel/kernel.cc'.
Thus it should be located in the BSS. That said, it might be normal that
you're observing a page-table base inside the program image. Is
0x10159000 inside your BSS? You can check this via 'genode-arm-objdump'
or instrument the Page_slab::alloc method to check wether it uses the
initial block for this page table.

Cheers
Martin

On 08.08.2014 09:14, Praveen B wrote:
> Hi Stefan,
>          I am working along with Chirag to port Genode on imx6. 
>
> We inserted the existing RAM regions in Platform::_ram_regions.( We
> rechecked it with linux kernel source code for imx6) But still we are
> getting page fault on every access to new Rom_module.
>
> I tried to track the memory allocation what I understood is, 
> In map_local() call,
> when inserting into page tables in "_insert_second_level()" function
> in short_translation_table.h file of base-hw, slab->phys_addr() and
> slab->virt_addr() return 0 after kernel initialization. So it creates
> a new page table and inserting into it. Inserting the same
> values(phys:10000000, virt:1000) as arguments of map_local() function
> in platform.cc. 
> When I print the address of new page table created, I found that it is
> in the range of Program Image.(address of pt is 10159000, and program
> image range is (10001000-10189fa4).
>
> I wonder if the memory allotted is clashing with program memory.
> Or,
> Can it be the issue with MMDC controller of imx6? Because no other
> board in base-hw uses MMDC controller, do we need to implement the
> interface for MMDC in imx6?
>
> Thanks and Regards
>
> Praveen,
> IIT Madras
>
>
>
> On Tue, Jul 29, 2014 at 6:43 PM, Stefan Kalkowski
> <stefan.kalkowski at ...1...
> <mailto:stefan.kalkowski at ...1...>> wrote:
>
>     Hi,
>
>     On 07/28/2014 11:28 AM, chirag garg wrote:
>     > Hi stefan,
>     >
>     > Thanks a lot in Advance,
>     >
>     > We are trying to debug the " Failed to communicate Thread Event
>     ". And we
>     > found that Platform is not getting Initialized, we are facing
>     Problem in
>     > the Platform constructor located in file :
>     base-hw/src/coe/platform.cc
>     >
>     > In the Platform () constructor
>     >
>     > Rom_module * rom_module = new (core_mem_alloc())
>     >             Rom_module(header->base, header->size, (const
>     > char*)header->name);
>     >
>     > is not getting executed(giving page fault) .  Do you know what
>     could be the
>     > problem ?
>
>     Do you've inserted the right existent RAM regions within your
>     Platform::_ram_regions definitions? If you added incorrect RAM regions
>     the "core_mem_alloc()" allocator of core will insert invalid page
>     table
>     entries in kernel/core's page table, and any access to the memory
>     of the
>     new Rom_module (returned by core_mem_alloc()) will fault.
>
>     But it's just guessing. Again, it is up to you to investigate what
>     exact
>     memory access is responsible for the fault.
>
>     Regards
>     Stefan
>
>     >
>     >
>     > Regards
>     >
>     > Chirag Garg
>     > IIT Madras , Rise Lab
>     >
>     >
>     >
>     >
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