On 31/10/2023 01:04, Mario Marietto wrote: > Hello, > > We are a team of linux enthusiasts who are trying to boot Xen on a > Samsung XE303C12 Chromebook aka "snow" > following the suggestions in the slide show presentation here: > > https://www.slideshare.net/xen_com_mgr/xpds16-porting-xen-on-arm-to-a-new-soc-julien-grall-arm > > This device uses an exynos5250 SOC dual core 1.7 GHz with 2 MB RAM, it is > a Samsung armv7 chip with virtualization extensions. > > In particular, we have it working fairly well both on the bare metal with > a recent 6.1.59 Linux LTS kernel and also with a recent 5.4.257 LTS Oh, these are old... Although there should be no noticeable changes against v6.1. v5.4 is not recent. It is four years old! > kernel with KVM, the older LTS kernel version is used to test KVM because > support for KVM on arm v7 was removed from Linux around kernel version > 5.7. So we know we have the hypervisor mode enabled because we were able > to use it with KVM. > > For Xen, we are using the latest Debian build of Xen 4.17 for the Debian > armhf architecture: ... > > In this case,the kernel is able to use the exynos-drm kernel to start > the fb0 device. But with Xen we get this error with exynos-drm: > > devuan-bunsen kernel: [drm] Exynos DRM: using 14400000.fimd device for > DMA mapping operations > devuan-bunsen kernel: exynos-drm exynos-drm: bound 14400000.fimd (ops > 0xc0d96354) > devuan-bunsen kernel: exynos-mixer 14450000.mixer: > [drm:exynos_drm_register_dma] *ERROR* Device 14450000.mixer lacks > support for IOMMU Hi Mario, I don't test DRM on my Exynos boards, so my knowledge is limited, but isn't this the answer? > devuan-bunsen kernel: exynos-drm exynos-drm: failed to bind > 14450000.mixer (ops 0xc0d97554): -22 > devuan-bunsen kernel: exynos-drm exynos-drm: adev bind failed: -22 > devuan-bunsen kernel: exynos-dp: probe of 145b0000.dp-controller > failed with error -22 And that's the final confirmation that display did not probe successfully. > > > Any ideas why booting the same Linux kernel that results in a working > X.org display on the bare metal instead as dom0 on Xen would cause the > display to remain dark, but most other basic functions would work, such > as network, disk, and USB ? thanks. BTW, it's usually good to Cc the maintainer as well, not only the mailing list :). scripts/get_maintainer.pl will tell you the maintainers of Exynos and Exynos DRM. Best regards, Krzysztof
