Re: X on old (non-x86) Linux guests

[Andrew Randrianasulu]

On Wednesday, April 28, 2021, Andrew Randrianasulu <randrianasulu@gmail.com> wrote:

On Monday, April 26, 2021, BALATON Zoltan <balaton@eik.bme.hu> wrote:

Hello,

On Mon, 26 Apr 2021, Dr. David Alan Gilbert wrote:

 Over the weekend I got a Red Hat 6.x (not RHEL!) for Alpha booting
under QEMU which was pretty neat.  But I failed to find a succesful
combination to get X working; has anyone any suggestions?

Adding Andrew who has experimented with old X framebuffer so he may remember something more but that was on x86.

Sorry, I still away from my desktop (with notes/logs), not sure when return.. 

I do not think I tried something that old.. Kernel 2.2 i guess, before any attempt at r128 drm Kernel module was written (in 2.4?) and so before ddx attempted to use that (as it tries by default in much newer distros) 

I tried Last debian for alpha, (5.0.x?) on qemu, it had bugs in cirrusfb in 2.6.26 Kernel so i compiled like 2.6.32.last inside emulated system.. This made fb works, But still there was no X for me... (can't recall exact error - May be even sigabort or sigbus - but do not count on my memory on this... /) 

Notes i used for launching qemu - 

https://virtuallyfun.com/wordpress/2014/02/19/alpha-linux-on-qemu/

But Sadly pre-compressed disk image from that post really gone (it uses funny error Page telling you to use login/password, yet file can't be downloaded...) 

Upd: 

https://web.archive.org/web/20191021110430/https://vpsland.superglobalmegacorp.com/old/install/linux/DecAlpha/alpha-linux.7z

This May give you kernel/initrd/disk image..

 That distro was from around 2000; the challenge is since we don't have
VESA on non-x86, we can't change mode that way, so generic XF86_SVGA
doesn't want to play with any of the devices.

 I also tried the ati device, but the accelerated mach64 driver
didn't recognise that ID.

The ati-vga partially emulates an ATI Rage128 Pro so it won't work with mach64 driver that is older and while functionally similar has different registers. You probably need to load aty128fb and then set a mode with fbset then may need to edit X conf but I forgot which option was neded, something about UseFb or similar so it won't try to change mode itself but use the already set Linux FB because otherwise it did not detect the card properly but I don'r remember the details so may be wrong. Also some 2D accel is emulated so may work without disabling it but I think has some bugs so it may have glitches.

 Has anyone found any combo that works?
I suspect using one of the existing devices, lying about PCI ID, and
then turning off all accelerations might have a chance but I've not got
that far.

Changing the PCI ID may not help as these ATI chips have different registers so only compatible with the right drivers. I've tried to use current ati-vga with a Mac ROM that expects mach64 but it did not work.

It may help to add -trace enable="ati*" and maybe also enable some debug defines in ati_int.h to see if it accesses the card at all but with the right driver that works with Rage128Pro it should produce some picture at least in fb console and we could run X with it on x86 before.

More info on ati-vga is here: https://osdn.net/projects/qmiga/wiki/SubprojectAti

By the way, last time I've experimented with it I've found that mouse pointer getting out of sync and jumping around is probably a result of mouse acceleration on the host is not taken into account when tracking guest pointer position. Is that possible and is there a way to fix it?

Regards,
BALATON Zoltan