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Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system
From: |
Xu, Anthony |
Subject: |
Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode |
Date: |
Fri, 12 May 2017 18:55:43 +0000 |
> On 12/05/2017 01:55, Xu, Anthony wrote:
> > Hi Paolo,
> >
> > In KVM mode, seems A20 is ignored.
> > Do you see any potential issue here?
>
> No; recent processors don't have A20 at all.
I mean A20 in guest, not A20 in host.
Guest is running on old platform, it tries to control A20 through port 92 like
what SeaBios does.
QEMU/KVM does handle port 92 access to set correct env->a20_mask,
but QEMU/KVM ignores A20 status when handling guest memory access.
Since QEMU/KVM works well with SeaBios, does that imply SeaBios doesn't
generate address
larger than 0x100000 in real mode?
If that's the case, QEMU/TCG should work with SeaBios even with ignoring A20.
During SeaBios boot, there are >350 port 92 access, if we don't need to handle
A20,
we can make A20 configurable in Seabios, It may reduce SeaBios boot time.
Anthony
- [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Paolo Bonzini, 2017/05/11
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, no-reply, 2017/05/11
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, no-reply, 2017/05/11
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Kevin O'Connor, 2017/05/11
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Paolo Bonzini, 2017/05/11
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Kevin O'Connor, 2017/05/11
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Xu, Anthony, 2017/05/11
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Paolo Bonzini, 2017/05/12
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode,
Xu, Anthony <=
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Paolo Bonzini, 2017/05/12
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Kevin O'Connor, 2017/05/12
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Xu, Anthony, 2017/05/12
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Kevin O'Connor, 2017/05/12
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Xu, Anthony, 2017/05/12
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Kevin O'Connor, 2017/05/16
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Xu, Anthony, 2017/05/16
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Kevin O'Connor, 2017/05/16
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Xu, Anthony, 2017/05/16
- Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode, Paolo Bonzini, 2017/05/17