Ping?
Any thoughts on whether this is acceptable?
- Charles
>>> On 10/30/2012 at 08:59 PM, in message <50a0e561.5b74.009...@suse.com>,
>>> Charles
Arnold wrote:
> The VHD specification allows for up to a 2 TB disk size. The current
> implementation in qemu emulates EIDE and ATA-2 hardware which only allows
> for up to 127 GB. This disk size limitation can be overridden by allowing
> up to 255 heads instead of the normal 4 bit limitation of 16. Doing so
> allows disk images to be created of up to nearly 2 TB. This change does
> not violate the VHD format specification nor does it change how smaller
> disks (ie, <=127GB) are defined.
>
> Signed-off-by: Charles Arnold <carn...@suse.com>
>
> diff --git a/block/vpc.c b/block/vpc.c
> index b6bf52f..0c2eaf8 100644
> --- a/block/vpc.c
> +++ b/block/vpc.c
> @@ -198,7 +198,8 @@ static int vpc_open(BlockDriverState *bs, int flags)
> bs->total_sectors = (int64_t)
> be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
>
> - if (bs->total_sectors >= 65535 * 16 * 255) {
> + /* Allow a maximum disk size of approximately 2 TB */
> + if (bs->total_sectors >= 65535LL * 255 * 255) {qemu-devel@nongnu.org
> err = -EFBIG;
> goto fail;
> }
> @@ -524,19 +525,27 @@ static coroutine_fn int vpc_co_write(BlockDriverState
> *bs, int64_t sector_num,
> * Note that the geometry doesn't always exactly match total_sectors but
> * may round it down.
> *
> - * Returns 0 on success, -EFBIG if the size is larger than 127 GB
> + * Returns 0 on success, -EFBIG if the size is larger than ~2 TB. Override
> + * the hardware EIDE and ATA-2 limit of 16 heads (max disk size of 127 GB)
> + * and instead allow up to 255 heads.
> */
> static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
> uint8_t* heads, uint8_t* secs_per_cyl)
> {
> uint32_t cyls_times_heads;
>
> - if (total_sectors > 65535 * 16 * 255)
> + /* Allow a maximum disk size of approximately 2 TB */
> + if (total_sectors > 65535LL * 255 * 255) {
> return -EFBIG;
> + }
>
> if (total_sectors > 65535 * 16 * 63) {
> *secs_per_cyl = 255;
> - *heads = 16;
> + if (total_sectors > 65535 * 16 * 255) {
> + *heads = 255;
> + } else {
> + *heads = 16;
> + }
> cyls_times_heads = total_sectors / *secs_per_cyl;
> } else {
> *secs_per_cyl = 17;
