Re: [PATCH] setup.c: introduce __pa_symbol() and get ride of CPHYSADDR()

[Franck Bui-Huu <vagabon.xyz@gmail.com>]

Thiemo Seufer wrote:
> Franck Bui-Huu wrote:
>> Thiemo Seufer wrote:
>>> Franck Bui-Huu wrote:
>>>> -	if (CPHYSADDR(initrd_end) > PFN_PHYS(max_low_pfn)) {
>>>> +	if (__pa(initrd_end) > PFN_PHYS(max_low_pfn)) {
>>> ISTR this failed on O2, where kernel+initrd are loaded into KSEG0 but the
>>> PAGE_OFFSET is for XKPHYS.
>>>
>> I guess that you were meaning somthing like:
>>
>> LOADADDR    = 0xffffffff80004000
>> PAGE_OFFSET = 0xa800000000000000
>>
>> is that correct ?
> 
> Yes.
> 
>> If so could you explain the choice of these values
>> because I fail to understand it.
> 
> It allows to load a 64-bit kernel in KSEG0,

sorry to be ignorant of 64 bit kernels, but what's the point
to load them in KSEG0.

> and use short 2-instruction symbol references there.

do you mean "it allows to use only 2 'lui' instructions to load
a symbol address into a register" ?

Futhermore I don't see how some part of the kernel convert virtual
address into a physical one with such values. For example in setup.c,
the function resource_init() does:

	code_resource.start = virt_to_phys(&_text);
	code_resource.end = virt_to_phys(&_etext) - 1;
	data_resource.start = virt_to_phys(&_etext);
	data_resource.end = virt_to_phys(&_edata) - 1;

How does it work in this case ?

Thanks
		Franck