add hugepages option

add hugepages option

vm configuration
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hugepages: (any|2|1024)

any: we'll try to allocate 1GB hugepage if possible, if not we use 2MB hugepage
2: we want to use 2MB hugepage
1024: we want to use 1GB hugepage. (memory need to be multiple of 1GB in this case)

optionnal host configuration for 1GB hugepages
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1GB hugepages can be allocated at boot if user want it.
hugepages need to be contiguous, so sometime it's not possible to reserve them on the fly

/etc/default/grub : GRUB_CMDLINE_LINUX_DEFAULT="quiet hugepagesz=1G hugepages=x"

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>
Acked-by: Wolfgang Bumiller <w.bumiller@proxmox.com>