[SeaBIOS] about ZoneHigh occupying ram from last address of below 4G ram

[penghao122 at sina.com]

I'm using seabios 1.7.5-0 for  kvm ,and I find some problem when using windows 7 64bit bandvirtual machine.If I configure the windows 7 64bit vm memory to 8GB ,the vm can't boot up very often(some win7-64bit version easy to trigger) .I use trace-cmd tool to trace it ,the vm just scan from last ram of below 4G(0xc000_0000) to 4G address byte by byte.This is very time-consuming.From E820 table,the address range contain nothing(it is an address hole).
I query clue from seabios because I can't find any problems in kvm or qemu.
seabios keep a range of ram from last address below 4G as  zonehigh ram .I guess  the windows os see a not aligned ram address space and scan from 0xc000_0000. so I try to change the ZoneHigh to low address space (I choose 128MB,grub use from 1MB address space).after I changed,I can boot win7-64bit vm normally.
 
So I want to know whether changing ZoneHigh to 128MB can be a general modification.
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