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Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN |
Date: |
Wed, 21 Nov 2012 12:14:32 +1100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, Nov 20, 2012 at 10:55:50AM +0100, Alexander Graf wrote:
>
> On 20.11.2012, at 10:53, Peter Maydell wrote:
>
> > On 20 November 2012 09:29, Alexander Graf <address@hidden> wrote:
> >> On 19.11.2012, at 23:48, David Gibson wrote:
> >>> On Mon, Nov 19, 2012 at 05:26:45PM +0100, Alexander Graf wrote:
> >>>> On 13.11.2012, at 03:46, David Gibson wrote:
> >>>>> This patch therefore changes ppcemb_tlb_t to use a fixed 64-bit integer
> >>>>> which we know is sufficient for all the machines which use this
> >>>>> structure.
> >>>>
> >>>> hwaddr is always defined to 64bit by now.
> >>>
> >>> I know, but there aren't state save helpers for hwaddr, and there are
> >>> objections to creating them.
> >
> > (previous discussion on this point:
> > https://lists.gnu.org/archive/html/qemu-devel/2012-10/msg01456.html )
> >
> >> Sure, but you can just use the 64bit save helpers now that hwaddr ==
> >> uint64_t, no?
> >
> > That would be one approach. I'm a bit sceptical about putting hwaddr
> > fields in CPU state, though -- it's suggestive that something's
> > not modelled right. hwaddr is conceptually "big enough for the
> > biggest bus in the system", and no single component should have
> > internal state whose size depends on that.
Right, that's the reason I was given for not adding VMSTATE helpers
for hwaddr too.
But more directly, as long as hwaddr is a different type from
uint64_t, to me that at least admits the possibility that it could be
changed again some day. And if we're using a uint64_t based VMSTATE
helper on a type that could change, that could go badly wrong.
Basically it's a subtle and ungreppable dependency on the fact that a
hwaddr is actually a uint64_t, which seems like a bad idea.
> *shrug* I'm more than happy to get a patch that just converts all
> *the hwaddr fields in CPUState to uint64_t.
So.. does that mean you'll apply this one or not?
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 03/12] pseries: Move XICS initialization before cpu initialization, (continued)
[Qemu-devel] [PATCH 05/12] pseries: Allow RTAS tokens without a qemu handler, David Gibson, 2012/11/12
[Qemu-devel] [PATCH 09/12] pseries: Implement PAPR NVRAM, David Gibson, 2012/11/12
[Qemu-devel] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, David Gibson, 2012/11/12
- Re: [Qemu-devel] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, Alexander Graf, 2012/11/19
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, David Gibson, 2012/11/19
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, Alexander Graf, 2012/11/20
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, Peter Maydell, 2012/11/20
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, Alexander Graf, 2012/11/20
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN,
David Gibson <=
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, Alexander Graf, 2012/11/20
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, David Gibson, 2012/11/20
- Re: [Qemu-devel] [Qemu-ppc] [PATCH 08/12] target-ppc: Convert ppcemb_tlb_t to use fixed 64-bit RPN, Alexander Graf, 2012/11/21
[Qemu-devel] [PATCH 06/12] pseries: Add tracepoints to the XICS interrupt controller, David Gibson, 2012/11/12
[Qemu-devel] [PATCH 07/12] pseries: Split xics irq configuration from state information, David Gibson, 2012/11/12
[Qemu-devel] [PATCH 11/12] pseries: Fix bug in PCI MSI allocation, David Gibson, 2012/11/12
[Qemu-devel] [PATCH 12/12] pseries: Generate unique LIOBNs for PCI host bridges, David Gibson, 2012/11/12