Re: [Crash-utility] [Xen-devel] [PATCH] xen: Add support for dom0 with Linux kernel 3.19 and newer
On 21/01/16 20:13, Daniel Kiper wrote:
Linux kernel commit 054954eb051f35e74b75a566a96fe756015352c8
(xen: switch to linear virtual mapped sparse p2m list), which
appeared in 3.19, introduced linear virtual mapped sparse p2m
list. If readmem() reads p2m then it access this list using
physical addresses. Sadly, VMA to physical address translation
in crash requires access to p2m list. This means that we have
a chicken and egg problem. In general this issue must be solved
by introducing some changes in libxl, Linux kernel and crash
(I have added this task to my long TODO list). However, in dom0
case we can use crash_xen_info_t.dom0_pfn_to_mfn_frame_list_list
which is available out of the box. So, let's use it and make
at least some users happy.
I'm confused. How does a virtual address to (pseudo-)physical address
lookup require access to the p2m? Surely this is a walk of the page
tables followed by a M2P lookup on the MFN in the L1 PTE?
David