Re: [PATCH 1/9] linux-user: Diagnose incorrect -R size

[Richard Henderson]

On 3/6/23 04:56, Peter Maydell wrote:
> On Mon, 6 Mar 2023 at 02:14, Richard Henderson
> <richard.henderson@linaro.org> wrote:
> > Zero is the value for 'off', and should not be used with -R.
> > We have been enforcing host page alignment for the non-R
> > fallback of MAX_RESERVED_VA, but failing to enforce for -R.
>
> I'm pretty sure we have users who specifically use "-R 0" to
> ask for "definitely turn off any reserved VA".
> Here's a random example from an old gcc bug report:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60681
> and somebody using it via the environment variable:
> https://www.openembedded.org/pipermail/openembedded-core/2015-January/100572.html

Odd.

Well, it won't actually have the effect of "definitely turn off", it will merely leave 
things as per the default, which *will* enable reserved va for 32-bit guests on 64-bit hosts.

The only remaining question is whether we diagnose this oddness or silently accept it.  It 
feels like someone playing with options they don't actually understand and an error is 
warranted.


r~