[Crash-utility] [PATCH 0/7] Upgrade the remote access to a xen domain.

[Daniel Kiper]

On Tue, Nov 19, 2013 at 06:46:39AM -0500, Don Slutz wrote:
> From: Don Slutz <dslutz at verizon.com>
>
> Currently crash 4.0 and later using the code:
>
> http://lists.xen.org/archives/html/xen-devel/2013-11/msg02569.html
>
> There is some very limited documention on crashes remote ptotocol in:
>
> http://lists.xen.org/archives/html/xen-devel/2013-11/msg02352.html
>
> and some fixes in the attachment 0001-xen-crashd-Connect-crash-with-domain.patch
> from the 1st link above.
>
> How ever there are issues with the current code:
>
> 1) The remote protocol has a minor issue (which I have not been able to
>    happen) based on the fact TCP/IP is stream based protocol.  This means
>    a RECV or a SEND may not do the fully requested size of data.  In fact
>    the current code assumes that the amount of data that a SEND is called
>    with will all be read with a single RECV.
>
> 2) The most common mismatch between crash and older kernels is
>    phys_base.  In the remote case, see if the remote server supports
>    vitrual memory access, and if so, see if phys_base can be retreived.
>
> 3) crash assumes that the remote system is active and can not return
>    currect IP and SP to do a better back trace.
>
> 4) enable a non-active mode of remote access.
>
> This patch set attempts to fix these:
>
> The fix for #1 I have called NIL mode (patch 1).
> The fix for #2 uses get_remote_phys_base (patch 3).
> The fix for #3 uses get_remote_regs (patch 5).
> The fix for #4 uses special file /dev/xenmem (patch 7).

Where is this file created? In guest or in host. Is it done by udev?
Where is driver for this file?

>   It also REMOTE_NIL() to indicate "remote paused system".
>
> Don Slutz (7):
>   Add NIL mode to remote.
>   remote_proc_version: NULL terminate passed buffer on error.
>   Add get_remote_phys_base.
>   Add remote_vtop.
>   bt: get remote live registers if possible.
>   Add get_remote_cr3
>   Add support for non-live remote.
>
>  defs.h   |   8 +-
>  kernel.c |  25 +++-
>  memory.c |  25 +++-
>  remote.c | 462 +++++++++++++++++++++++++++++++++++++++++++++++++++++----------
>  x86_64.c |  24 ++++
>  5 files changed, 465 insertions(+), 79 deletions(-)

I have done quick review. It looks quite nice. There are two nitpicks
for me. Please do not use camelCase (I have found one in patch 3 in
struct _remote_context) and do not add Emacs directives at the end
of files (this is Xen specific stuff).

Daniel