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Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support |
Date: |
Fri, 20 Jun 2014 11:10:47 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Jun 20, 2014 at 02:07:05AM -0400, Paolo Bonzini wrote:
>
>
> ----- Messaggio originale -----
> > Da: "Aurelien Jarno" <address@hidden>
> > A: "Sanjay Lal" <address@hidden>
> > Cc: "James Hogan" <address@hidden>, address@hidden, "Peter Maydell"
> > <address@hidden>,
> > address@hidden, "Gleb Natapov" <address@hidden>, "Paolo Bonzini"
> > <address@hidden>
> > Inviato: Giovedì, 19 giugno 2014 23:47:34
> > Oggetto: Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support
> >
> > On Thu, Jun 19, 2014 at 12:34:24PM -0700, Sanjay Lal wrote:
> > >
> > > On Jun 19, 2014, at 9:27 AM, Aurelien Jarno <address@hidden> wrote:
> > >
> > > > On Tue, Jun 17, 2014 at 11:10:35PM +0100, James Hogan wrote:
> > > >> In KVM mode the bootrom is loaded and executed from the last 1MB of
> > > >> DRAM.
> > > >
> > > > What is the reason for that? I am not opposed to that, but if it is
> > > > really needed, it means that loading a bootloader into the flash area
> > > > (for example YAMON) won't work and that this should be forbidden to the
> > > > user.
> > > >
> > >
> > > In trap and emulate mode, both the kernel and userland run in user mode on
> > > the processor. Virtual addresses >= 0x80000000 are only accessible in
> > > kernel mode, and the default flash area (VA: 0xbfc00000/PA: 0x1fc00000)
> > > falls in this range.
> > >
> > > We therefore decided to relocate the bootloader to the last 1MB of RAM.
> > > This area is excluded from the RAM ranges supplied to the kernel, so it
> > > should not be accessible to the user.
> > >
> >
> > Thanks for the explanation. It means we should disable the support for
> > booting from the flash (using -pflash) in KVM mode, as it would simply
> > not work.
>
> My idea was to add a machines-specific option umkernel=on, and require it
> in order to run KVM. Later we can add umkernel=on support for TCG as well,
> while umkernel=off with KVM requires virtualization extensions.
>
> The same option can disable pflash boot.
>
> What do you think?
For what I understand the current KVM support in MIPS uses trap and
emulate and thus doesn't need hardware support, just a recent kernel
with the option enabled. That's why I do wonder if there is a real point
in supporting UM kernels in TCG mode.
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
address@hidden http://www.aurel32.net
- [Qemu-devel] [PATCH v5 11/12] target-mips: Enable KVM support in build system, (continued)
- [Qemu-devel] [PATCH v5 11/12] target-mips: Enable KVM support in build system, James Hogan, 2014/06/17
- [Qemu-devel] [PATCH v5 05/12] target-mips: get_physical_address: Add KVM awareness, James Hogan, 2014/06/17
- [Qemu-devel] [PATCH v5 06/12] kvm: Allow arch to set sigmask length, James Hogan, 2014/06/17
- [Qemu-devel] [PATCH v5 01/12] target-mips: Reset CPU timer consistently, James Hogan, 2014/06/17
- [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, James Hogan, 2014/06/17
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, Aurelien Jarno, 2014/06/19
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, Sanjay Lal, 2014/06/20
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, Aurelien Jarno, 2014/06/19
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, Paolo Bonzini, 2014/06/20
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, James Hogan, 2014/06/20
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support,
Aurelien Jarno <=
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, Paolo Bonzini, 2014/06/20
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, Aurelien Jarno, 2014/06/20
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, James Hogan, 2014/06/20
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, James Hogan, 2014/06/20
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, Paolo Bonzini, 2014/06/20
- Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support, Aurelien Jarno, 2014/06/20
[Qemu-devel] [PATCH v5 09/12] hw/mips: In KVM mode, inject IRQ2 (I/O) interrupts via ioctls, James Hogan, 2014/06/17
[Qemu-devel] [PATCH v5 02/12] hw/mips/cputimer: Don't start periodic timer in KVM mode, James Hogan, 2014/06/17
[Qemu-devel] [PATCH v5 08/12] target-mips: Call kvm_mips_reset_vcpu() from mips_cpu_reset(), James Hogan, 2014/06/17
[Qemu-devel] [PATCH v5 04/12] target-mips: get_physical_address: Add defines for segment bases, James Hogan, 2014/06/17