Re: Reserving physical memory at boot time

Pavel Machek (pavel@ucw.cz)
Thu, 6 Mar 2003 22:26:07 +0100


Hi!

> > OK, with feeling:
> >
> > I agree with you since the boot protocol is well-defined.
> >
> > Just to be clear, my comment was referring to
> > Documentation/kernel-parameters.txt, not to any C code.
> >
> > And it would really be helpful to catch issues like this soon
> > after they happen...
> >
>
> Unfortunately last time I commented on this the response was roughly
> "well, the patch already made it into Linus' kernel, it's too late to
> fix it now." That isn't exactly a very helpful response.
>
> The mem= parameter has the semantic in the i386/PC boot protocol that
> it specifies the top address of the usable memory region that begins
> at 0x100000. It's a bit of a wart that the boot loaders have to be
> aware of this, but it's so and it's been so for a very long time.

Really? So user has to know where ACPI tables are and specify less
than that on mem= command line? That seems very
counter-intuitive. [Ahha, its probaly okay because e820 saves you.]

What do you pass on 4GB machine as mem= parameter? AFAIK those beasts
have hole at 3.75G. [Hopefully bigmem machines have working e820
tables?]

Pavel

-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]
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