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Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system
From: |
Kevin O'Connor |
Subject: |
Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode |
Date: |
Thu, 11 May 2017 10:53:12 -0400 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
On Thu, May 11, 2017 at 01:35:28PM +0200, Paolo Bonzini wrote:
> Ignore env->a20_mask when running in system management mode.
Thanks Paolo. I don't think this patch will help SeaBIOS though. The
SeaBIOS SMM handler doesn't do much - it doesn't even access ram above
1MiB. See SeaBIOS' code in src/fw/smm.c:handle_smi().
Instead, the SeaBIOS code does a cpu state backup/restore to switch
into 32bit mode. I thought the A20 state would be part of that cpu
backup/restore. However, looking at the Intel SDM docs now, it's not
really clear to me how the processor "inhibits" A20 when in SMM mode -
does it save/restore that state on SMI/RSM or does it have special
logic to ignore A20 while in SMM mode?
-Kevin
- [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 <=
- 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, 2017/05/12
- 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