[Python-Dev] How can we use 48bit pointer safely?

Joao S. O. Bueno jsbueno at python.org.br
Fri Mar 30 09:08:50 EDT 2018


Not only that, but afaik  Linux could simply raise that 57bit virtual
to 64bit virtual without previous
warning on any version change.

On 30 March 2018 at 08:55, Ronald Oussoren <ronaldoussoren at mac.com> wrote:
>
>
> On Mar 30, 2018, at 08:31 AM, INADA Naoki <songofacandy at gmail.com> wrote:
>
> Hi,
>
> As far as I know, most amd64 and arm64 systems use only 48bit address
> spaces.
> (except [1])
>
> [1]
> https://software.intel.com/sites/default/files/managed/2b/80/5-level_paging_white_paper.pdf
>
> It means there are some chance to compact some data structures.
> I point two examples below.
>
> My question is; can we use 48bit pointer safely?
>
>
> Not really, at least some CPUs can also address more memory than that. See
> <https://lwn.net/Articles/717293/> which talks about Linux support for
> 57-bit virtual addresses and 52-bit physical addresses.
>
> Ronald
>
>
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