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

Kevin O'Connor kevin at koconnor.net
Tue Apr 14 18:45:38 CEST 2015

On Tue, Apr 14, 2015 at 11:57:08PM +0800, penghao122 at sina.com wrote:
> 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.

I haven't seen any other reports of issues like this with Win7.  I
suspect something else is going on.  Please provide the full debug log
(as described at: http://seabios.org/Debugging ) with an unmodified
seabios from both a succesful boot event and a failed boot event.


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