[Xen-devel] Physical memory start contraints in the Linux kernel (Was: Re: Xen osstest on Calxeda midway progress (Was: Re: [xen-unstable test] 21486: tolerable FAIL - PUSHED))

[Julien Grall]

On 11/12/2013 02:41 PM, Russell King - ARM Linux wrote:
> On Tue, Nov 12, 2013 at 02:35:10PM +0000, Julien Grall wrote:
>> During some debugging on the Arndale and Midway, I found another
>> constraint with CONFIG_ARM_PATCH_PHYS_VIRT.
>> I have noticed that all the kernel physical addresses must be lower than
>> the corresponding virtual addresses. So the delta offset compute in
>> __fixup_pv_table (arch/arm/kernel/head.S) must always be negative.
>> If this assertion is not validated, when the kernel will browse the
>> memory bank (sanity_check_info in arch/arm/mm/mmu.c), __phys(...) will
>> compute a wrong address and will result to consider all memory bank as
>> highmem.
>>
>> After digging in the code, it seems it's due to some optimization during
>> opcode fixup in __fixup_a_pvtable. Is it a wanted constraint?
>
> Are you talking about the code in v3.12 or the code in -next ?

I was talking about 3.12. I have just checked -next and my issue seems 
to be fixed by the commit f52bb722547f43caeaecbcc62db9f3c3b80ead9b.
I should have checked earlier, thanks.

-- 
Julien Grall