Re: [hatari-devel] Linux user-space crashes

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On 19.6.2024 18.54, Nicolas Pomarède wrote:
> I made some tries with --ide-master bb-rootfs.img (CPU MMU is enabled in 
> all cases) :
>
>   - no prefetch, no CE, no data cache : 'ls' works, no segfault
>
>   - prefetch, no CE, no data cache : segfault
>
>   - CE, no data cache : segfault
>
>   - no prefetch, no CE, data cache ON : no segfault
>
> This looks different to what you wrote "has never behaved correctly when 
> data-cache is enabled", because in my tests I see that it works with 
> data cache and the cause of the segfault would be related to the 
> difference between normal and prefetch (as CE also includes prefetch we 
> can leave it on the side for now)
>
> Could you check if you still get segfault with data cache on and no 
> prefetch / no CE ?

If both CE & prefetch are disabled, so is data-cache.

If data-cache _is_ allowed without them (see attached patch), then Linux 
kernel crashes already when it reaches init:
---------------------
....
Run /init as init process
  with arguments:
    /init
  with environment:
    HOME=/
    TERM=linux
    BOOT_IMAGE=vmlinux
random: crng init done
watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [init:30]
---------------------


	- Eero

diff --git a/src/m68000.c b/src/m68000.c
index 05028391..818220fd 100644
--- a/src/m68000.c
+++ b/src/m68000.c
@@ -389,12 +389,8 @@ void M68000_CheckCpuSettings(void)
 	changed_prefs.cachesize = 0;
 
 	/* while 020 had i-cache, only 030+ had also d-cache */
-	if (changed_prefs.cpu_model < 68030 ||
-	    !ConfigureParams.System.bCpuDataCache ||
-	    !(changed_prefs.cpu_compatible || changed_prefs.cpu_cycle_exact))
+	if (changed_prefs.cpu_model < 68030)
 		changed_prefs.cpu_data_cache = false;
-	else
-		changed_prefs.cpu_data_cache = true;
 
 	/* Update SPCFLAG_MODE_CHANGE flag if needed */
 	check_prefs_changed_cpu();