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I would like some assistance filing two xen related bugs


Four years ago I ran into two issues with the xen support in Debian - at that time I forgot to report these issues back to Debian. Now, when setting up a new machine I ran into the second of these issues (and it turned out that the first one was still there).

Scenario: An Amd 3700X CPU on a X570 based motherboard

1) Using EFI boot will incorrectly add "no-real-mode edd=off" to the kernel (xen) command line:

For me this manifested (four years ago) as not getting a working console. Digging around it turned out that the GRUB script generator (20_linux_xen) emitted code that checked if $grub_platform was either "pc" or "". When using EFI boot this variable gets set to "efi". This mismatch causes the script to add "no-real-mode edd=off" to the command line.

In latest stable Debian this works, although it still adds those two kernel (xen) command line options. The fix is very simple:

--- /etc/grub.d/20_linux_xen~   2020-06-28 12:37:08.394067050 +0200
+++ /etc/grub.d/20_linux_xen    2020-06-28 12:41:46.056439654 +0200
@@ -125,7 +125,7 @@
   lmessage="$(gettext_printf "Loading Linux %s ..." ${version})"
   sed "s/^/$submenu_indentation/" << EOF
        echo    '$(echo "$xmessage" | grub_quote)'
-        if [ "\$grub_platform" = "pc" -o "\$grub_platform" = "" ]; then
+ if [ "\$grub_platform" = "pc" -o "\$grub_platform" = "efi" -o "\$grub_platform" = "" ]; then
             xen_rm_opts="no-real-mode edd=off"

2) CPU frequency scaling does not seem to work.

This one was a bit trickier to figure out. You can see my mail (from 2016) to the xen users mailing list here: http://xen.1045712.n5.nabble.com/CPU-frequency-scaling-there-be-dragons-here-td5732214.html

The core issue is that the xen-acpi-processor module is not loaded during boot which in turn causes the xen/drivers/cpufreq stuff to not get initialized. Again, the fix was very simple - just add xen-acpi-processor to /etc/modules. I guess this should be done whenever installing the xen hypervisor?

I would very much appreciate some quick pointers on how to properly report this so that I don't have to dig up my posts to the xen users mailing list to figure out something I already should know.


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