Hi Eero,
while the workaround will shut up the unexpected interrupt messages, it
still does not prevent that interrupt from happening.
falcon_hblhandler() will not set the IPL sufficiently high for that, and
I do not know whether permanently setting IPL 4 will quiesce other
system interrupts.
Setting tt_scu.sys_mask zero is indeed the preferred option.
If you or Christian want to submit a patch to that effect, I'll gladly
add my review tag.
Cheers,
Michael
On 20/06/24 02:43, Eero Tamminen wrote:
Hi,
During the development of Atari TT / MegaSTe SCU support for Hatari
emulator, it was noticed that m68k Linux does not properly initialize
SCU registers / IRQ handlers on boot.
Currently Linux freezes at boot and spews "unexpected interrupt"
messages constantly on TT.
Nicolas Pomarède and Christian Zietz investigated:
* Issue to be due to VBL IRQ handler removal [1]
* boot to succeed if either 0x00 is written to the SCU sys_mask
(preferred), or handler is provided for VEC_INT4 [2] when SCU is used
Christian has verified the issue and its workaround on real Atari TT.
- Eero
[1]
https://github.com/torvalds/linux/commit/1fa0b29f3a43f9dd8080d24cd16790b15ef963f5
[2]
https://git.tuxfamily.org/hatari/hatari.git/tree/tools/linux/0004-WA-avoid-unexpected-SCU-interrupts.patch
