Re: [PATCH for xen-4.4] libxl: add option for discard support to xl disk configuration

[Olaf Hering <olaf@aepfle.de>]

On Thu, Jan 30, Ian Campbell wrote:

> On Thu, 2014-01-30 at 17:25 +0100, Olaf Hering wrote:
> > This change does not break ABI. Instead of adding a new member ->discard_enable
> > to struct libxl_device_disk the existing ->readwrite member is reused.
> Looks like it changes the libxlu ABI though. Or maybe that's totally
> internal?

DiskParseContext is used internal, there is no public header for it.

> TBH -- if you (==suse I guess?) are contemplating carrying this as a
> backport even before 4.4 is out the door we should probably be at least
> considering a freeze exception for 4.4. George CCd for input. (I
> appreciate that "backport=>freeze exception" is a potentially slippery
> slope/ripe for abuse...)

It will make less work for SUSE if this change would be incorporated
into 4.4, and later replaced with the "final" version I sent out today.
However, its small and will be easy to port forward to 4.4.X.

The risk of including such change is small as it requires a patched qemu
which actually does discard (1.7?), a patched frontend driver (pvops
3.15?) before the codepaths it enables are actually executed.

Olaf