Re: [PATCH v2] tools/libs/light: update xenstore entry when setting max domain memory

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, Apr 20, 2022 at 10:04:26AM +0200, Juergen Gross wrote:
> libxl_domain_setmaxmem() called during "xl mem-max" should update the
> domain's memory/static-max Xenstore node, as otherwise "xl mem-set"
> won't be able to set the memory size to the new maximum.

Setting domain's memory higher than the original mem-max only works on
PV and maybe PVH guest, right? Because on HVM, QEMU is told about
maxmem when starting a guest, and allocates some stuff from this address
(vga buffer, pci rom I think) so trying to give HVM guest more memory
after the fact is probably not going to go smoothly.

> Adjust the related comments and documentation accordingly.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> V2:
> - adjust comments and docs (Anthony Perard)

Maybe `man xl` should be updated as well. In the section about `xl
mem-max`, there is:
    "Note however that the initial maxmem value is still used as an
    upper limit for xl mem-set.  Also note that calling xl mem-set will
    reset this value."

That wouldn't be true anymore with this patch.

Thanks,

-- 
Anthony PERARD