Ubuntu 19.10 will be 64 bit only

[Dmitry Timoshkov]

"Erich E. Hoover" <erich.e.hoover at gmail.com> wrote:

> On Fri, Jun 21, 2019 at 6:41 AM Rosanne DiMesio <dimesio at earthlink.net> wrote:
> > ...
> > I'm not qualified to explain the technical issues, beyond saying Wine does it the same way as Windows (WoW64). I need help framing an answer in terms a typical Ubuntu user can understand that I can put in the FAQ and on the forum.
> 
> Well, part of the problem is that we don't implement WoW64 the exact
> same way Windows does.  All the 32-bit Windows routines have thunks
> that transition to 64-bit code, call the 64-bit API equivalent, and
> then transition back to 32-bit code.

That's probably true only for low level things like ntdll, user32, gdi32
and ws2_32, but everything else that doesn't need to access kernel level
OS functionality (like gdiplus/windowscodecs) don't need to perform the
32-bit to 64-bit transition.

>  Our 32-bit libraries call the
> 32-bit Linux equivalents, since this is massively easier and "just
> works".  I vaguely remember a conversation a number of years ago where
> someone talked about doing similar thunking to Windows and there was
> concern that it is too hard to get this thunking correct for every API
> call, but I don't remember the details as to why that's the case.

win16 is very small in comparison with win32, so it was relatively easy
to implement it on top of 32-bit code, it's practically impossible to do
the same thing to implement 32-bit on top of 64-bit.

-- 
Dmitry.