Re: [Xen-devel] Design doc of adding ACPI support for arm64 on Xen - version 2

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.08.15 at 04:11, <zhaoshenglong@xxxxxxxxxx> wrote:
> 1. Copy and change some EFI and ACPI tables
> -------------------------------------------

A key thing I'm missing here is reasoning of why this copying approach
is needed in the first place. Remember that on the x86 side we get
away without any such copying-and-changing. Yet the farther you
diverge from x86's model, the more changes you'll need to common
Xen code in e.g. Linux.

> All these tables will be copied to Dom0 memory except that the reused
> tables(DSDT, SPCR, etc) will be mapped to Dom0.

Which again seems odd - such tables should be considered MMIO
(despite living in RAM), and hence not be part of Dom0's memory
assignment.

> 3. Dom0 gets grant table and event channel irq information
> -----------------------------------------------------------
> As said above, we assign the hypervisor_id be "XenVMM" to tell Dom0 that
> it runs on Xen hypervisor.
> 
> For grant table, add two new HVM_PARAMs: HVM_PARAM_GNTTAB_START_ADDRESS
> and HVM_PARAM_GNTTAB_SIZE.

Mind explaining why you need this on ARM when x86 gets away without?

Jan


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