[Qemu-devel] Re: [PATCH V5 15/29] pci: typedef pcibus_t as uint64_t instead of uint32_t.

[Michael S. Tsirkin]

On Fri, Oct 09, 2009 at 03:28:48PM +0900, Isaku Yamahata wrote:
> This patch is preliminary for 64bit bar.
> For 64bit bar support, change pcibus_t which represents
> pci bus addr/size from uint32_t to uint64_t.
> And also change FMT_pcibus for printf.
> 
> In pci_update_mapping() checks 32bit overflow.
> So the check must be updated too.
> 
> Signed-off-by: Isaku Yamahata <address@hidden>

That's all fine, but if you look at users implementing
map io, they do: cpu_register_physical_memory()
on the address they are given.  And if target_phys_addr_t is 32 bit,
this will silently truncate the address.

So I would like to understand how this will all
work on 32 bit systems.

> ---
>  hw/pci.c |    9 ++++++++-
>  hw/pci.h |    4 ++--
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index c0ae66a..e7f8fb4 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -524,7 +524,14 @@ static void pci_update_mappings(PCIDevice *d)
>                         mappings, we handle specific values as invalid
>                         mappings. */
>                      if (last_addr <= new_addr || new_addr == 0 ||
> -                        last_addr == PCI_BAR_UNMAPPED) {
> +                        last_addr == PCI_BAR_UNMAPPED ||
> +
> +                        /* Now pcibus_t is 64bit.
> +                         * Check if 32 bit BAR wrap around explicitly.
> +                         * Without this, PC ide doesn't work well.
> +                         * TODO: remove this work around.
> +                         */
> +                        last_addr >= UINT32_MAX) {
>                          new_addr = PCI_BAR_UNMAPPED;
>                      }
>                  } else {
> diff --git a/hw/pci.h b/hw/pci.h
> index 8a187c2..8fbd45e 100644
> --- a/hw/pci.h
> +++ b/hw/pci.h
> @@ -71,8 +71,8 @@ extern target_phys_addr_t pci_mem_base;
>  #define PCI_DEVICE_ID_VIRTIO_BALLOON     0x1002
>  #define PCI_DEVICE_ID_VIRTIO_CONSOLE     0x1003
>  
> -typedef uint32_t pcibus_t;
> -#define FMT_PCIBUS                      PRIx32
> +typedef uint64_t pcibus_t;
> +#define FMT_PCIBUS                      PRIx64
>  
>  typedef void PCIConfigWriteFunc(PCIDevice *pci_dev,
>                                  uint32_t address, uint32_t data, int len);
> -- 
> 1.6.0.2