Hi, > On 3 Jun 2020, at 19:09, Julien Grall <jul...@xen.org> wrote: > > > > On 03/06/2020 18:13, CodeWiz2280 wrote: >> Hi Julien, > > Hello, > > In general, we avoid top post on xen-devel, instead we reply inline. I > believe gmail should allow you to do it :). > >> The offset is already applied to the memory nodes in the device tree, >> meaning a direct Linux boot from uboot would have only the 36-bit addresses >> in the device tree (0x8_0000_0000 and 0x8_8000_0000). Linux would start >> executing from a 32-bit address space however and then switch over to the >> aliased 36-bit addresses in the device tree as discussed below by >> early_paging_init(). >> I had to add the 32-bit memory node 0x8000_0000 in uboot in place of the >> 0x8_0000_0000 node otherwise Xen would detect the 32-bit processor and panic >> on "Unable to detect the first memory bank" in domain_build.c. > > So for 32-bit Xen requires to have the first bank below 4GB. This is because > you can't boot from a physical address above 32-bit. > > Obviously, this check wouldn't work on your platform because all your memory > will be above 4GB.
I think that the Keystone board has low memory accessible at 2 different address (one low and one high). I would here suggest to have a dtb with 2 regions (one under 4GB and one over) and remove from the region over 4G the area already addressed by the region under 4GB. Does that make sense ? Cheers Bertrand > >> If I leave only the 36-bit addresses in the device tree and skip past the >> panic check in domain_build.c, then I could not get the dom0 kernel to boot >> at all. I believe I would only see "Serial input to DOM0" and nothing else >> at that point. > > Which would make sense per above. > >> Yes, leaving LPAE support on for the kernel is preferred. > > Ok, so the solution I suggested below should work. Unfortunately, I don't > have time to work on it. Although, I would be more than happy to answers > questions and reviewing the patches. > > Would you be willing to have a try to implement it? > > Cheers, > > -- > Julien Grall
