Re: [PATCH ] VMSPLIT config options (with default config fixed)

[Mark Lord <lkml@rtr.ca>]

Jan Engelhardt wrote:
>
> This sort of testing reminds me of Linus's 100->1000 Hz change
> ("I chose 1000 originally partly as a way to make sure that people that
>     assumed HZ was 100 would get a swift kick in the pants.")
> 
> Could we also do that with VMSPLIT?
> ("Let's choose VMSPLIT_2G to make sure that i386-people that assumed
> PAGE_OFFSET was 0xC0000000 would get...")

Mmm.. bad idea.  As much as I'd like the default to be 3GB_OPT, that would
be a big impact to userspace, and there's no point in breaking everyone's
machines when advanced users can just reconfig/recompile to get what they want.

>> Hm, I wonder if we could have a more fine-grained choice of the
>> boundary? There are also systems around with e.g. 1.25G or 1.5G of
>> main memory.
>>
> Maybe something like:
>         config VMSPLIT_1G
>                 bool "1G/3G user/kernel split"
>         config VMSPLIT_X
>                 bool "Manual split"
> endchoice
...

Yes, that looks like a good idea.

Cheers