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Re: [Qemu-devel] [RFC 7/7] fw_cfg DMA for x86
From: |
Marc Marí |
Subject: |
Re: [Qemu-devel] [RFC 7/7] fw_cfg DMA for x86 |
Date: |
Wed, 22 Jul 2015 11:06:39 +0200 |
On Tue, 21 Jul 2015 18:14:40 +0100
Peter Maydell <address@hidden> wrote:
> On 21 July 2015 at 17:03, Marc Marí <address@hidden> wrote:
> > Enable fw_cfg for x86 machines. Create new machine to avoid
> > incompatibilites.
>
> > @@ -1391,7 +1399,14 @@ FWCfgState *pc_memory_init(MachineState
> > *machine, option_rom_mr,
> > 1);
> >
> > - fw_cfg = bochs_bios_init();
> > + if (guest_info->fw_cfg_dma) {
> > + as = g_malloc(sizeof(*as));
> > + address_space_init(as, ram_below_4g, "pc.as");
> > + fw_cfg = bochs_bios_init(as, BIOS_CFG_DMA_ADDR);
> > + } else {
> > + fw_cfg = bochs_bios_init(NULL, 0);
> > + }
> > +
>
> As with ARM: what's the rationale for choosing this particular
> AddressSpace as the target for fw_cfg DMA? (I'm not saying it's
> wrong, necessarily -- I was just surprised we didn't just use
> the system address space.)
>
> thanks
> -- PMM
I took something that seemed logical for me, as the BIOS will be
working in 32 bits. But, as with ARM, I'm not really sure which
address space should I use for this purpose. I'd appreciate some help
in the issue.
Thanks
Marc