Thanks for your reply. I've already changed to boot with the xen.efi directly without grub2. Now I can see all the cpu cores, but I can't use the mouse or keyboard. What's more, the memory seems to be problematic too. 'xl dmesg' shows :
(XEN) Unknown cachability for MFNs 0x80000-0x8ffff
(XEN) Unknown cachability for MFNs 0xfeda8-0xfedab
(XEN) Initial low memory virq threshold set at 0x4000 pages.
(XEN) HVM1 restore: bad CR4 0x1526f0
(XEN) HVM1 restore: failed to load entry 2/0
(d4) Relocating guest memory for lowmem MMIO space disabled
(d4) No RAM in high memory; setting high_mem resource base to 100000000
Even though finally the domain 4 booted, using libxc api xc_domain_maximum_gpfn(xen->xchandle, xen->domainid) cannot get the max_gpfn.
> Date: Mon, 30 Nov 2015 03:31:13 -0700
> From: JBeulich@xxxxxxxx
> To: quizy_jones@xxxxxxxxxxx
> CC: xen-devel@xxxxxxxxxxxxx
> Subject: Re: [Xen-devel] boot xen use legacy bios
>
> >>> On 29.11.15 at 12:26, <quizy_jones@xxxxxxxxxxx> wrote:
> > I got the problem of multiple cores CPU cannot be fully used when using UEFI
> > mode. It is suggested that I should be boot the xen in legacy mode. How is it
> > done?
>
> For BIOSes that don't have a Legacy Support Module, booting in
> non-EFI mode just won't work. See my other reply. For BIOSes
> that do have an LSM, you may need to find the setup option to
> turn it on if it's not on by default.
>
> But generally questions like this belong on xen-users, not xen-devel.
>
> Jan
>
>
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