Re: [Qemu-devel] [PATCH 04/19] libqos/ahci: Add command header helpers

[Paolo Bonzini <pbonzini@redhat.com>]

On 30/01/2015 19:41, John Snow wrote:
> +/* Set the #cx'th command of port #px. */
> +void ahci_set_command_header(AHCIQState *ahci, uint8_t px,
> +                             uint8_t cx, AHCICommandHeader *cmd)
> +{
> +    uint64_t ba = ahci->port[px].clb;
> +    ba += cx * sizeof(AHCICommandHeader);
> +
> +    cmd->flags = cpu_to_le16(cmd->flags);
> +    cmd->prdtl = cpu_to_le16(cmd->prdtl);
> +    cmd->prdbc = cpu_to_le32(cmd->prdbc);
> +    cmd->ctba = cpu_to_le64(cmd->ctba);

Modifying cmd is uglyish, and especially it might hide bugs that only
happen on big endian system.  Please copy to a local AHCICommandHeader
variable before adjusting for host endianness.

Paolo

> +    memwrite(ba, cmd, sizeof(AHCICommandHeader));
> +}