This series aims to fix an issue of booting a guest with many PVSCSI disk
controllers (>=16). Currently, booting such a guest result in exhausting
available memory in high-zone which leads to guest crash.
The 1st patch improve PVSCSI memory consumption by removing an unnecessary
contraint of allocating a page-aligned memory.
The 2nd patch modifies SeaBIOS high-zone allocator to fallback to low-zone
in case high-zone is exhausted. This is possible because high-zone is used
only by 32-bit code which don't care if allocation is from high-zone or low-zone
and just uses high-zone because it has more space. However, in case there
is no more memory in high-zone, it makes sense to utilize remaining memory
in low-zone to still be able to boot guest successfully.
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