Re: [PATCH v3 00/11] xen: Initial kexec/kdump implementation

From: H. Peter Anvin
Date: Wed Dec 26 2012 - 23:02:56 EST


On 12/26/2012 06:18 PM, Daniel Kiper wrote:
Hi,

This set of patches contains initial kexec/kdump implementation for Xen v3.
Currently only dom0 is supported, however, almost all infrustructure
required for domU support is ready.

Jan Beulich suggested to merge Xen x86 assembler code with baremetal x86 code.
This could simplify and reduce a bit size of kernel code. However, this solution
requires some changes in baremetal x86 code. First of all code which establishes
transition page table should be moved back from machine_kexec_$(BITS).c to
relocate_kernel_$(BITS).S. Another important thing which should be changed in that
case is format of page_list array. Xen kexec hypercall requires to alternate physical
addresses with virtual ones. These and other required stuff have not been done in that
version because I am not sure that solution will be accepted by kexec/kdump maintainers.
I hope that this email spark discussion about that topic.


I want a detailed list of the constraints that this assumes and therefore imposes on the native implementation as a result of this. We have had way too many patches where Xen PV hacks effectively nailgun arbitrary, and sometimes poor, design decisions in place and now we can't fix them.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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