Thanks for sharing the logs.
By comparing them the only relevant difference I noticed is the following one:
* In kernel 6.8.0-11 (which is the one working), the kernel attempts to load
hyperv_fb, but fails:
[ 29.103795] hyperv_fb: No memory for framebuffer
[ 29.104204] hyperv_fb: probe of 5620e0c7-8062-4dce-aeb7-520c7ef76171
failed with error -12
This triggers the fallback to hyperv_drm, which then successfully initializes
a DRM-based framebuffer:
[ 29.222515] hyperv_drm 5620e0c7-8062-4dce-aeb7-520c7ef76171: [drm] fb0:
hyperv_drmdrmfb frame buffer device
* In kernel 6.8.0-62 (which is not working), the kernel successfully loads
hyperv_fb:
[ 20.738004] hyperv_fb: Synthvid Version major 3, minor 5
[ 20.738124] hyperv_fb: Screen resolution: 1024x768, Color depth: 32,
Frame buffer size: 8388608
Therefore there is no hyperv_drm initialization. Thus, the system ends
up using hyperv_fb exclusively, which provides only the default 1024x768
framebuffer, and does not support resolution changes, unlike hyperv_drm.
This change in behavior is due to the following commit:
- 20ee2ae8c589 fbdev/hyperv_fb: Fix logic error for Gen2 VMs in hvfb_getmem()
which fixes the bug that makes hyperv_fb fail.
Moreover, comparing Noble with Debian Unstable, I noticed that in Ubuntu's
config we have:
- CONFIG_FB_HYPERV=m
while in Debian:
- # CONFIG_FB_HYPERV is not set
This is most probably the reason why screen resizing works in Debian but not on
Ubuntu.
To confirm this hypothesis, can you please blacklist the hyperv_fb module on
Noble (6.8 or 6.11 or 6.14) and verify if the problem is still reproducible?
To do this you can execute:
$ echo "blacklist hyperv_fb" | sudo tee /etc/modprobe.d/blacklist-hyperv_fb.conf
$ sudo update-initramfs -u
$ sudo reboot
Confirm that the module is indeed not loaded:
$ lsmod | grep hyperv_fb
$ modprobe --showconfig | grep hyperv_fb
Please execute the steps above and paste here the output of the
commands. Please attach also the dmesg as usual. Thanks
** Changed in: linux-meta-hwe-6.11 (Ubuntu)
Status: Incomplete => Confirmed
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https://bugs.launchpad.net/bugs/2115068
Title:
Ubuntu 24.04+ arm64: screen resolution fixed to 1024x768 with last
kernel update
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