* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
@ 2012-11-12 19:12 Charles Arnold
2012-11-13 10:46 ` Paolo Bonzini
0 siblings, 1 reply; 10+ messages in thread
From: Charles Arnold @ 2012-11-12 19:12 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf, stefanha
Ping?
Any thoughts on whether this is acceptable?
- Charles
>>> On 10/30/2012 at 08:59 PM, in message <50A0E561.5B74.0091.0@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 <carnold@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;
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
2012-11-12 19:12 [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks Charles Arnold
@ 2012-11-13 10:46 ` Paolo Bonzini
2012-11-13 10:56 ` Stefano Stabellini
0 siblings, 1 reply; 10+ messages in thread
From: Paolo Bonzini @ 2012-11-13 10:46 UTC (permalink / raw)
To: Charles Arnold; +Cc: Kevin Wolf, qemu-devel, stefanha, Stefano Stabellini
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?
Paolo
> - Charles
>
>>>> On 10/30/2012 at 08:59 PM, in message <50A0E561.5B74.0091.0@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 <carnold@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;
>
>
>
>
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
2012-11-13 10:46 ` Paolo Bonzini
@ 2012-11-13 10:56 ` Stefano Stabellini
2012-11-14 16:25 ` Thanos Makatos
0 siblings, 1 reply; 10+ messages in thread
From: Stefano Stabellini @ 2012-11-13 10:56 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Charles Arnold, Kevin Wolf, thanos.makatos, xen-devel,
Stefano Stabellini, qemu-devel@nongnu.org, stefanha@redhat.com
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 <50A0E561.5B74.0091.0@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 <carnold@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;
> >
> >
> >
> >
>
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
2012-11-13 10:56 ` Stefano Stabellini
@ 2012-11-14 16:25 ` Thanos Makatos
2012-11-14 16:35 ` Paolo Bonzini
0 siblings, 1 reply; 10+ messages in thread
From: Thanos Makatos @ 2012-11-14 16:25 UTC (permalink / raw)
To: Stefano Stabellini, Paolo Bonzini
Cc: Charles Arnold, Kevin Wolf, xen-devel@lists.xensource.com,
qemu-devel@nongnu.org, stefanha@redhat.com
We don't use qemu's VHD driver in XenServer. Instead, we use blktap2 to create a block device in dom0 serving the VHD file in question, and have qemu open that block device instead of the VHD file itself.
> -----Original Message-----
> From: Stefano Stabellini [mailto:stefano.stabellini@eu.citrix.com]
> Sent: 13 November 2012 10:56
> To: Paolo Bonzini
> Cc: Charles Arnold; qemu-devel@nongnu.org; Kevin Wolf;
> stefanha@redhat.com; Stefano Stabellini; xen-devel@lists.xensource.com;
> Thanos Makatos
> Subject: Re: [PATCH] block: vpc support for ~2 TB disks
>
> 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
> > >>>> <50A0E561.5B74.0091.0@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 <carnold@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;
> > >
> > >
> > >
> > >
> >
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
2012-11-14 16:25 ` Thanos Makatos
@ 2012-11-14 16:35 ` Paolo Bonzini
2012-11-15 16:46 ` Charles Arnold
2012-11-15 17:48 ` Thanos Makatos
0 siblings, 2 replies; 10+ messages in thread
From: Paolo Bonzini @ 2012-11-14 16:35 UTC (permalink / raw)
To: Thanos Makatos
Cc: Charles Arnold, Kevin Wolf, xen-devel@lists.xensource.com,
Stefano Stabellini, qemu-devel@nongnu.org, stefanha@redhat.com
Il 14/11/2012 17:25, Thanos Makatos ha scritto:
> We don't use qemu's VHD driver in XenServer. Instead, we use blktap2
> to create a block device in dom0 serving the VHD file in question,
> and have qemu open that block device instead of the VHD file itself.
Yes, the question is how you handle disks bigger than 127GB, so that
QEMU can do the same.
Paolo
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
2012-11-14 16:35 ` Paolo Bonzini
@ 2012-11-15 16:46 ` Charles Arnold
2012-11-15 17:00 ` Paolo Bonzini
2012-11-15 17:48 ` Thanos Makatos
1 sibling, 1 reply; 10+ messages in thread
From: Charles Arnold @ 2012-11-15 16:46 UTC (permalink / raw)
To: Thanos Makatos, Paolo Bonzini
Cc: Kevin Wolf, xen-devel@lists.xensource.com, qemu-devel@nongnu.org,
stefanha@redhat.com, Stefano Stabellini
>>> On 11/14/2012 at 09:35 AM, in message <50A3C853.4010809@redhat.com>, Paolo
Bonzini <pbonzini@redhat.com> wrote:
> Il 14/11/2012 17:25, Thanos Makatos ha scritto:
>> We don't use qemu's VHD driver in XenServer. Instead, we use blktap2
>> to create a block device in dom0 serving the VHD file in question,
>> and have qemu open that block device instead of the VHD file itself.
>
> Yes, the question is how you handle disks bigger than 127GB, so that
> QEMU can do the same.
>
In analyzing a 160 GB VHD fixed disk image created on Windows 2008 R2, it appears that
MS is also ignoring the CHS values in the footer geometry field in whatever
driver they use for accessing the image. The CHS values are set at 65535,16,255
which obviously doesn't represent an image size of 160 GB.
This patch only extends the existing qemu driver to allow a larger image by allowing
more heads. On real hardware, only 4 bits would be allowed for heads but we don't
have that restriction in qemu.
- Charles
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
2012-11-15 16:46 ` Charles Arnold
@ 2012-11-15 17:00 ` Paolo Bonzini
0 siblings, 0 replies; 10+ messages in thread
From: Paolo Bonzini @ 2012-11-15 17:00 UTC (permalink / raw)
To: Charles Arnold
Cc: Kevin Wolf, Thanos Makatos, xen-devel@lists.xensource.com,
Stefano Stabellini, qemu-devel@nongnu.org, stefanha@redhat.com
Il 15/11/2012 17:46, Charles Arnold ha scritto:
>>> We don't use qemu's VHD driver in XenServer. Instead, we use blktap2
>>> >> to create a block device in dom0 serving the VHD file in question,
>>> >> and have qemu open that block device instead of the VHD file itself.
>> >
>> > Yes, the question is how you handle disks bigger than 127GB, so that
>> > QEMU can do the same.
>> >
> In analyzing a 160 GB VHD fixed disk image created on Windows 2008 R2, it appears that
> MS is also ignoring the CHS values in the footer geometry field in whatever
> driver they use for accessing the image. The CHS values are set at 65535,16,255
> which obviously doesn't represent an image size of 160 GB.
Thanks, this would have been useful in the commit message.
The patch looks good,
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo
> This patch only extends the existing qemu driver to allow a larger image by allowing
> more heads. On real hardware, only 4 bits would be allowed for heads but we don't
> have that restriction in qemu.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
2012-11-14 16:35 ` Paolo Bonzini
2012-11-15 16:46 ` Charles Arnold
@ 2012-11-15 17:48 ` Thanos Makatos
1 sibling, 0 replies; 10+ messages in thread
From: Thanos Makatos @ 2012-11-15 17:48 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Charles Arnold, Kevin Wolf, xen-devel@lists.xensource.com,
Stefano Stabellini, qemu-devel@nongnu.org, stefanha@redhat.com
I'm not sure I understand your question. In XenServer blktap2 we set CHS to 65535*16*255 in the VHD metadata for disks larger than 127GB. We don't really care about these values, we just store them in the VHD metadata.
> -----Original Message-----
> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
> Sent: 14 November 2012 16:36
> To: Thanos Makatos
> Cc: Stefano Stabellini; Charles Arnold; qemu-devel@nongnu.org; Kevin
> Wolf; stefanha@redhat.com; xen-devel@lists.xensource.com
> Subject: Re: [PATCH] block: vpc support for ~2 TB disks
>
> Il 14/11/2012 17:25, Thanos Makatos ha scritto:
> > We don't use qemu's VHD driver in XenServer. Instead, we use blktap2
> > to create a block device in dom0 serving the VHD file in question,
> and
> > have qemu open that block device instead of the VHD file itself.
>
> Yes, the question is how you handle disks bigger than 127GB, so that
> QEMU can do the same.
>
> Paolo
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
@ 2012-10-31 2:59 Charles Arnold
2012-11-19 11:50 ` Stefan Hajnoczi
0 siblings, 1 reply; 10+ messages in thread
From: Charles Arnold @ 2012-10-31 2:59 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf
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 <carnold@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) {
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;
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks
2012-10-31 2:59 Charles Arnold
@ 2012-11-19 11:50 ` Stefan Hajnoczi
0 siblings, 0 replies; 10+ messages in thread
From: Stefan Hajnoczi @ 2012-11-19 11:50 UTC (permalink / raw)
To: Charles Arnold; +Cc: Kevin Wolf, qemu-devel
On Tue, Oct 30, 2012 at 08:59:32PM -0600, 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 <carnold@suse.com>
Thanks, applied to my block-next tree:
https://github.com/stefanha/qemu/commits/block-next
Stefan
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2012-11-19 11:50 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-11-12 19:12 [Qemu-devel] [PATCH] block: vpc support for ~2 TB disks Charles Arnold
2012-11-13 10:46 ` Paolo Bonzini
2012-11-13 10:56 ` Stefano Stabellini
2012-11-14 16:25 ` Thanos Makatos
2012-11-14 16:35 ` Paolo Bonzini
2012-11-15 16:46 ` Charles Arnold
2012-11-15 17:00 ` Paolo Bonzini
2012-11-15 17:48 ` Thanos Makatos
-- strict thread matches above, loose matches on Subject: below --
2012-10-31 2:59 Charles Arnold
2012-11-19 11:50 ` Stefan Hajnoczi
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