On Sun, Sep 12, 2021 at 9:02 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> - running_on_qemu = (memcmp(&PAGE0->pad0, "SeaBIOS", 8) == 0);
> + running_on_qemu = (memcmp(absolute_pointer(&PAGE0->pad0), "SeaBIOS", 8) == 0);
This seems entirely the wrong thing to do, and makes no sense. That
"&PAGE0->pad0" is a perfectly valid pointer, and that's not where the
problem is.
The problem is "PAGE0" itself:
#define PAGE0 ((struct zeropage *)__PAGE_OFFSET)
which takes that absolute offset and creates a pointer out of it.
IOW, _that_ is what should have the "absolute_pointer()" thing, and in
that context the name of that macro and its use actually makes sense.
No?
An alternative - and possibly cleaner - approach that doesn't need
absolute_pointer() at all might be to just do
extern struct zeropage PAGE0;
and then make that PAGE0 be defined to __PAGE_OFFSET in the parisc
vmlinux.lds.S file.
Then doing things like
running_on_qemu = !memcmp(&PAGE0.pad0, "SeaBIOS", 8);
would JustWork(tm).
Hmm?
Linus
