On Tue, 13 Nov 2012, Paolo Bonzini wrote:
> Il 12/11/2012 20:12, Charles Arnold ha scritto:
> > Ping?
> >
> > Any thoughts on whether this is acceptable?
>
> I would like to know what is done by other platforms. Stefano, any idea
> about XenServer?
>
I am not sure, but maybe Thanos, that is working on blktap3, knows, or
at least knows who to CC.
> > - 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;
> >
> >
> >
> >
>
