[OpenBIOS] [commit] r739 - trunk/openbios-devel/libopenbios

[Mark Cave-Ayland]

Igor Kovalenko wrote:

> This ofmem_update_translations call is supposed to keep available
> physical memory ranges up-to-date. There are no other places where we
> do update available phys ranges. Virtual ranges and MMU translations
> we update at the same time; since virtual allocations and MMU
> translations are not affected at this call site the resulting lists of
> virtual ranges and MMU translations are not changed.
> 
> The only thing which may change here is actual placement of
> "translations" property value, so if you keep pointer to previous
> location it may be stale after update call.
> 
> What is the issue you are solving here?

I've just done some more experimentation with r738 by replacing the call 
to ofmem_update_translations() with its constituent functions.

If I replace it with the following:

	ofmem_update_memory_available(s_phandle_memory,
			ofmem->phys_range, get_ram_size());

- Everything works okay.

If I replace it with:

	ofmem_update_memory_available(s_phandle_memory,
			ofmem->phys_range, get_ram_size());

	ofmem_update_memory_available(s_phandle_mmu,
			ofmem->virt_range, -1ULL);

- Everything still works okay.

If I replace it with:

	ofmem_update_memory_available(s_phandle_memory,
			ofmem->phys_range, get_ram_size());

	ofmem_update_memory_available(s_phandle_mmu,
			ofmem->virt_range, -1ULL);

	ofmem_update_mmu_translations();

- Forth starts misbehaving and the translate call crashes.


This points the finger at ofmem_update_mmu_translations(). Given that 
this is a physical memory allocation, is there any reason why I 
shouldn't change r739 to instead of removing ofmem_update_translations() 
to just replace it with:

	ofmem_update_memory_available(s_phandle_memory,
			ofmem->phys_range, get_ram_size());

This is because for a physical allocation there is no need to update the 
virt_range nor the MMU translations. And it seems to work so far in testing.


ATB,

Mark.

-- 
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
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