"KONG, Gangfeng" wrote:
>
> Hi,
>
> I need to put more physical memory (>1GB) into kernel space of 2.4.
> As my understanding, though 2.4 can support up to 64G RAM, the
> kernel space is still limited to 950MB.
>
> If I like to extend kernel space to around 3GB (both virtual and physical),
> may I simply lift:
> __PAGE_OFFSET
> to the appreciated value I like? if it's not true, what else I have to
> worry about?
The x86 architecture has a 4GM virtual address size, which
is split between user space (below PAGE_OFFSET) and kernel
space (above PAGE_OFFSET). Just be aware that if you change
PAGE_OFFSET to give the kernel more virtual space, you are
also going to *reduce* the maximum virtual size of any
user process.
Somewhere there's a patch that gives kernel and user
space both >3GB virtual space, presumably by doing
lots of pgdir switching. I don't know the details,
maybe a post to linux-mm@kvack.org would get you
some better info. I think that patch may be against
a 2.2-era kernel, however.
Cheers,
-- Joe
"Thanks to Microsoft, I am now blind in both eyes. They have
rolled back in my head so many times this week that they
are apparently stuck there now."
- Jonathan Rickman, regarding M$ anti-open-source PR.
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