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Re: [PATCH] pci: add romsize property
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH] pci: add romsize property |
Date: |
Tue, 19 Jan 2021 17:51:32 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 |
+pflash
On 12/18/20 7:27 PM, Paolo Bonzini wrote:
> This property can be useful for distros to set up known-good ROM sizes for
> migration purposes. The VM will fail to start if the ROM is too large,
> and migration compatibility will not be broken if the ROM is too small.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> hw/pci/pci.c | 19 +++++++++++++++++--
> hw/xen/xen_pt_load_rom.c | 14 ++++++++++++--
> include/hw/pci/pci.h | 1 +
> 3 files changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index d4349ea577..fd25253c2a 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -67,6 +67,7 @@ static void pcibus_reset(BusState *qbus);
> static Property pci_props[] = {
> DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> DEFINE_PROP_STRING("romfile", PCIDevice, romfile),
> + DEFINE_PROP_UINT32("romsize", PCIDevice, romsize, -1),
> DEFINE_PROP_UINT32("rombar", PCIDevice, rom_bar, 1),
> DEFINE_PROP_BIT("multifunction", PCIDevice, cap_present,
> QEMU_PCI_CAP_MULTIFUNCTION_BITNR, false),
> @@ -2106,6 +2107,11 @@ static void pci_qdev_realize(DeviceState *qdev, Error
> **errp)
> bool is_default_rom;
> uint16_t class_id;
>
> + if (pci_dev->romsize != -1 && !is_power_of_2(pci_dev->romsize)) {
> + error_setg(errp, "ROM size %d is not a power of two",
> pci_dev->romsize);
> + return;
> + }
Some cloud providers already complained the pow2 check in the pflash
device (wasting host storage). Personally I find using pow2 easier
and safer.
The pow2 check looks like a separate change however, maybe add in a
separate patch? Or maybe not :)
Regards,
Phil.