Re: ioremap()/PCI sickness in 2.4.18-rc2 (FIXED ALMOST)

Alan Cox
2002-02-20T22:52:34Z

> Sigh .... I am only using 2 GB on a 4GB capable processor (actually
> a 64 GB capable processor). Looks like a patch is needed. Who is
> maintaining vmalloc.c at present so I know who to submit a patch
> to?

Actually you are using a 64Gb capable processor that is only capable of
sanely addressing 4Gb at a time, total across both user and kernel space
and takes a hefty hit whenever you switch which 4Gb you are peering at.

If you want to make sensible use of even 4Gb user/4Gb kernel you need to
take a page table reload at syscall time and deal with quite messy handling
for copy to/from user.

[If someone from Intel disagrees please do so publically - I'd love to have
someone prove the limit can be dealt with 8)]