Re: [PATCH 6/6] enable syscalls on x86_64

[Luca Dariz]

Hi,

Il 22/02/23 15:44, Sergey Bugaev ha scritto:
> On Sun, Feb 12, 2023 at 8:04 PM Luca Dariz <luca@orpolo.org> wrote:
> > -// TODO: test it before dropping ud2
> > -       ud2
>
> Hi; could you please tell me how you are testing this?
>
> What userland code do you run? How does it make syscalls, does it use
> lcall $7, $0 like on i386, or what?

yes this is the entry point through the call gate, it works with any 
32-bit binary that you can compile on  32-bit hurd. For testing you can 
use a ramdisk, like the installer, or some simple executable (I have my 
own scripts [0] that I would like to polish and integrate somewhere).

Note that on a 64-bit kernel the linux drivers are not integrated, and 
user-space drivers currently don't work because of missing interrupt 
support (and maybe something else).

As far as I understand from Intel's datasheets, it should be possible to 
use a far call also from a 64-bit userspace, but I couldn't find the 
right way so far, so I was looking at the syscall/sysret mechanisms instead.

Luca

[0] https://gitlab.com/luckyd/gnumach/-/tree/prepare64_wip/tests