On 25.07.2018 16:01, Maxime Villard wrote:
> Le 25/07/2018 à 15:54, Siddharth Muralee a écrit :
>> Hello,
>> While going through sys/arch/amd64/pmap.h, I came across
>> KERN_BASE[1] and confused it for KERNBASE[2]. Looking deeper into the
>> same I think someone made the same mistake in dtrace_isa.c{3](I might
>> be wrong).
>> I compared how the same variable was used in amd64[4] and
>> i386[5]. There seems to be a mismatch. I computed the values for
>> KERN_BASE and KERNBASE for amd64 and
>>
>> * KERN_BASE = 0x800000000000
>> * KERNBASE = 0xffffffff80000000
>>
>> I think this may be an error. However, the names are definitely a bit
>> confusing and there is no documentation to suggest what they are for.
>
> They are not the same. KERNBASE is the base where .text etc are located.
> KERN_BASE is where the kernel map begins (VM_MIN_KERNEL_ADDRESS).
>
> In fact, KERN_BASE is incorrect, there should be a VA_SIGN_NEG() around the
> multiplication. I've always known this, but I don't know if it's really
> harmful, so by default I've never fixed it.
I propose to either rename or fix KERN_BASE according to VA_SIGN_NET().
These names are confusing.
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