Re: [PATCHv6 0/10] kexec: extend kexec hypercall for use with pv-ops kernels

[David Vrabel <david.vrabel@citrix.com>]

On 25/06/13 20:27, Daniel Kiper wrote:
> On Mon, Jun 24, 2013 at 06:42:11PM +0100, David Vrabel wrote:
> 
> [...]
> 
>> Changes since v4 (v5 was not posted to the list):
>>
>> - _rsvd -> _pad in one of the public ABI structures.
>> - Fix bug where trailing pages were not zeroed. This fixes loading a
>>   64-bit Linux kernel using a more recent version of kexec-tools.
> 
> Why? I do not see why trailing pages must be zeroed. I am afraid that
> this way you are only masking bug in kexec-tools. I think it is better
> to do bisect on it and find out which patch introduces a bug.

The load sub-ob is defined such that the range (dest_maddr + buf_size,
dest_maddr + dest_size] is zeroed.  If the caller asks for lots of
trailing zeros then we should do this (regardless of how pointless this
is).  I do note that this is not very well documented and I will improve
this.

kexec-tools calculates the checksum of the image including the trailing
zeroed region which is why the exec would fail.

If you want to improve kexec-tools to load fewer zeroed pages, be my guest.

> Please prepare next version of these patches and repost with
> kexec-tools patches. They are integral part of new Xen kexec
> implementation and it is worth to review both patch series together.

The kexec-tools patches haven't changed and I don't see any merit in
reposting them until the Xen patches are applied.

David