On Tue, Mar 2, 2021 at 7:57 PM LinAdmin <linad...@quickline.ch> wrote: > On 02.03.21 02:08, Ryutaroh Matsumoto wrote: > >> Bullseye 64 Bit does more or less work. There arise problems > >> when you install a desktop with media players which deliver > >> audio and should give output to the headphone plug and HDMI. > > Diederik reported probably the same problem to the linux-rpi-kernel > > list as > > http://lists.infradead.org/pipermail/linux-rpi-kernel/2021-February/008002.html > > For that problem, black listing vc4.ko at cmdline.txt prevents the problem > > http://lists.infradead.org/pipermail/linux-rpi-kernel/2021-February/008007.html > > > >> Unfortunately the Bullseye 32 Bit kernel seems not to boot, > >> because the support of USB looks broken: > > Debian kernel team does not support booting 32-bit kernel > > on 64-bit ARM, as told by Ben > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=971059#12 > > That approach may be reasonable for many arm architectures > which do not show considerably lower performance on 64 bit > compared to 32 bit. > > For the Pi4 this is an undeniably good reason not to use 64 > bit because contrary to common believes the 32 bit kernel > has no problems with 8 GB of RAM.
highmem is a huge problem by itself, and we plan to remove it in the future for 32-bit kernels across all architectures. We should probably add a boot-time warning in the mainline kernel as well for any such configuration. There is a small overhead in memory consumption for running a 64 bit kernel, but for configurations with more at least 512MB of RAM, you tend to be better off running a 64-bit kernel in order to make use of all the features, optimizations and errata workarounds that are missing in 32-bit kernels. Arnd