----- Original Message -----
> Hi Dave,
>
> One question:
>
> #define FILL_PML4() { \
> if (!(pc->flags & RUNTIME) || ACTIVE()) { \
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> I am confused that crash checks the flags in the FILL_PML4() macro, but
> not check that in other macros, such as FILL_PGD().
Good question -- I don't have a really good answer...
I think it's a legacy of an earlier time, but as I recall, the !RUNTIME check
was simply to ensure that it had been initialized at least once during session
initialization. I don't recall the reasoning behind the ACTIVE() check, other
than the fact that while it could never change in a dumpfile, conceivably it may
change during an active session in future kernels? However, I believe that once
FILL_PML4() is called in x86_64_init_kernel_pgd(), it really never needs to be
called again. So it pretty much makes the checks redundantly for the sake of
absolute surety.
Dave
>
> Could you tell me why we need to do this check?
>
> if (!IS_LAST_PML4_READ(vt->kernel_pgd[0])) \
> readmem(vt->kernel_pgd[0], KVADDR,
> machdep->machspec->pml4, \
> PAGESIZE(), "init_level4_pgt", FAULT_ON_ERROR); \
> machdep->machspec->last_pml4_read =
> (ulong)(vt->kernel_pgd[0]); \
> } \
> }
>
> Thanks,
> dou
>
>
>
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