[Qemu-devel] Re: [PATCH] pcnet: Fix sign extension: make ipxe work with >2G RAM

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

On Tue, Mar 15, 2011 at 10:47:22AM -0600, Alex Williamson wrote:
> From: Michael Brown <mcb30@ipxe.org>
> 
> The problem is with definitions in hw/pcnet.c such as:
> 
>   #define CSR_CRDA(S)      ((S)->csr[28] | ((S)->csr[29] << 16))
> 
> "(S)->csr[29]" is a uint16_t, but "(S)->csr[29] << 16" gets promoted to
> int, so the overall CSR_CRDA(s) is a (signed) int rather than a uint32_t.
> 
> This then gets assigned to a uint64_t using
> 
>   target_phys_addr_t crda = CSR_CRDA(s);
> 
> so when (S)->csr[29] has the high bit set, we end up with
> crda=0xffffffffxxxxxxxx.
> 
> From: Michael Brown <mcb30@ipxe.org>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> 
>  hw/pcnet.c |   30 +++++++++++++++---------------
>  1 files changed, 15 insertions(+), 15 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>