Re: Xen PVH domU start-of-day VCPU state

[Jürgen Groß <jgross@xxxxxxxx>]

On 25.05.20 18:04, Martin Lucina wrote:
> Hi,
>
> I'm trying to bootstrap a new PVH-only Xen domU OS "from scratch", to
> replace our existing use of Mini-OS for the early boot/low-level support
> layer in MirageOS. I've done this by creating new Xen bindings for Solo5
> [1], basing them on our existing virtio code [2].
>
> Unfortunately, I can't seem to get past the first few instructions on VCPU
> boot. Here's what I have at the moment (abridged):
>
>      .section .note.solo5.xen
>
>              .align  4
>              .long   4
>              .long   4
>              .long   XEN_ELFNOTE_PHYS32_ENTRY
>              .ascii "Xen\0"
>              .long   _start32
>
>      /* ... */
>
>      .code32
>
>      ENTRY(_start32)
>              cld
>
>              lgdt (gdt64_ptr)
>              ljmp $0x10, $1f
You need to setup virtual addressing and enable 64 bit mode before using
64-bit GDT.

See Mini-OS source arch/x86/x86_hvm.S


Juergen