On Sun, May 10, 2020 at 01:09:58PM +0100, Rui Salvaterra wrote: > Hi, Gabriel, > > On Sun, 10 May 2020 at 12:37, Gabriel Paubert <paub...@iram.es> wrote: > > > > I suspect the PowerMac6,7 is a 32 bit machine, given what you say below. > > Yes, of course, sorry for not being more explicit. :) > > > Well, extremely low is a bit of an exaggeration. On 32 bit x86, lowmem > > is 896MB. This is only 128MB higher than on your machine, or 16.7% more. > > My surprise wasn't the HIGHMEM split itself, but the fact that it's > needed at all. I have x86(-32) machines with over 3 GiB of usable RAM > which don't need HIGHMEM support.
Huh ? User space is 3GB on x86, but kernel uses highmem as soon as there is over ~1GB of physical RAM. And if I remember correctly user applications can also map 3GB on PPC32, 4GB on PPC32 applications running on 64 bit machines.
