Re: More progress to report
On Tue, Mar 2, 2021 at 7:57 PM LinAdmin <linadmin@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
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