Known problems with AmigaOS 4.1 on QEMU

1. Initial graphics mode is incorrect which results in strange blue white colors

   For some reason AmigaOS may not select the right graphics mode on boot and falls back to PAL LowRes which results in strange color dithering. Workaround is to select the last option to boot into LiveCD and select a better board specific mode from System / Prefs / ScreenMode. (ScreenMode prefs may take a long time to launch so wait some time like a minute or so after you've double clicked on it before trying again.) See screen shots showing the problem and workaround steps.

   Alternatively, you can patch the boot iso to change screenmode.prefs to use only a 16 bit mode so the selected mode and colors will be correct. This can be done by this binary patch kindly provided by Sebastian Bauer. This patch applies to iso with MD5 sum a9be88ab08c5883d6a6f14a12cd5b32f and should result in iso with MD5 sum 06ce410a7fc5f7dc236488f8ee76ad47. One can use

   bspatch Sam460InstallCD-53.58.iso Sam460InstallCD-53.58-patched.iso Sam460InstallCD-53.58.iso.bsdiff
   

   to apply the patch. Please note that you are responsible to comply with the license of AmigaOS and you're not allowed to distribute the iso.

2. Graphics problems on pegasos2 with SDL1

   This is caused by a bug in the PegasosII kernel in AmigaOS when using AltiVec optimisations that are enabled with the default G4 CPU. Using -cpu g3 instead may work around this. The same problem does not occur on amigaone and should be fixed in an upcoming AmigaOS update that ships a fixed pegasos2 kernel.

3. Memory size is limited to 1 gigabyte with pegasos2.rom (PegasosII firmware ROM)

   This may be fixed in the future but using BBoot without ROM already supports memory size up the the platform maximum of 2 gigabytes.

4. PCI cards such as network cards don't work with QEMU versions before v8.0.0 with pegasos2

   Use newer QEMU version where this was fixed.

5. SFS partitions don't show up on QEMU

   On pegasos2 before QEMU v8.1.0 a CPU known by AmigaOS such as -cpu 7457 or -cpu g3 must be selected. The PPC version of SmartFilesystem Kickstart module checks for specific CPUs and machine features and does not recognise the 7400 G4 CPU QEMU emulated by default in v8.0.0 and earlier. Replacing SmartFileSystem with a 68k version is also a possible work around but specifying an appropriate CPU is enough and fixes this problem. After QEMU v8.1.0 the default is -cpu 7457 so no explicit option is needed any more.

   On sam460ex the feature that SFS checks for was fixed in QEMU v9.0.0 so you should use that or newer.

6. The rtl8139 driver from AmigaOS 4.1FE Update 1 or 2 may not work correctly.

   This can be fixed by either downgrading to the version on the 4.1FE install CD or upgrading to an unreleased beta driver.

7. When using the ALSA audio backend on Linux sound may crackle.

   This can be avoided by adding -audiodev alsa,id=audio0,out.try-poll=off to QEMU command line. This option has changed to -audio in QEMU v8.2.0.

8. There is a delay during boot with siliconmotion502.chip driver version 53.10

   The older 53.9 version does not have this problem and it is fixed in version 53.12 available from OS4Depot but that latest version can only be installed after 4.1FE Update 2.

9. Crash while or after installing Update1 on sam460ex

   The libstdc++ included in Update1 has a bug that it uses lwsync instruction which is invalid on embedded PPC but only causes exception on e500 cores on real hardware. There's a patch to QEMU to allow this to work which is included in QEMU v4.0.0 so you should not see lwsync related crashes with newer QEMU versions.

10. Some programs randomly crash on sam460ex

    Some programs may crash sometimes. This happens less frequently in QEMU v5.0.0-rc2 so at least this version is recommended for AmigaOS. This seems to depend on speed of emulated CPU and only happens on fast systems but the exact cause is not yet known so it couldn't be fixed.