Xen devel - Apr 2007 - [PATCH][RFC] Support GPT (GUID Partition Table)

Hi,

I made a patch for GPT support.

As you see, this patch uses ad-hoc approach.
If you give me an advice, it would be appreciated

Signed-off-by: Shinya Kuwamura <kuwa@jp.fujitsu.com>
Signed-off-by: Tomohiro Takahashi <takatom@jp.fujitsu.com>

Thanks,
Tomohiro Takahashi.

diff -r 1bde28f762a6 -r 8e08fd1ffa24 tools/pygrub/src/pygrub
--- a/tools/pygrub/src/pygrub   Mon Apr 09 13:40:25 2007 -0600
+++ b/tools/pygrub/src/pygrub   Tue Apr 10 20:30:05 2007 +0900
@@ -58,6 +60,13 @@ def get_active_partition(file):
         # active partition has 0x80 as the first byte
         if struct.unpack("<c", buf[poff:poff+1]) ==
(''\x80'',):
             return buf[poff:poff+16]
+
+        # type=0xee: GUID partition table
+        # XXX assume the first partition is active
+        if struct.unpack("<c", buf[poff+4:poff+5]) ==
(''\xee'',):
+            os.lseek(fd, 0x400, 0)
+            buf = os.read(fd, 512)
+            return buf[24:40] # XXX buf[32:40]

     # if there''s not a partition marked as active, fall back to
     # the first partition




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On 11/4/07 08:48, "Takahashi Tomohiro" <takatom@jp.fujitsu.com>
wrote:
> I made a patch for GPT support.
I don''t see anything wrong with it, although won''t it always
be the first
legacy partition that is marked with type 0xee?

 -- Keir


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Hi Keir,
>>>>> On Wed, 11 Apr 2007 15:27:53 +0100
>>>>> keir@xensource.com(Keir Fraser)  said:
> 
> On 11/4/07 08:48, "Takahashi Tomohiro"
<takatom@jp.fujitsu.com> wrote:
> 
> > I made a patch for GPT support.
> 
> I don''t see anything wrong with it, although won''t it
always be the first
> legacy partition that is marked with type 0xee?
No, but this patch supports the second (or third, ...) legacy
partition marked with 0xee.
# I have no idea whether it is necessary well...

This patch has different problems. get_active_partition() returns a
entry of a legacy partition. Since the structure of GPT partition
entries differs from the structure of legacy partition entries, this
patch has the following problem:

 - pygrub cannot access a domain more than 2^32 * SECTOR_SIZE because
   get_fs_offset() treats the offset as a 32-bit integer. In GPT, the
   offset must be treated as 64-bit integer.

 - This patch returns a part of a GUID unique to the partition as
   legacy partition types. pygrub may misunderstand partition types.

I plan to fix this problem.

Best Regards,
-- 
  KUWAMURA Shin''ya

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Hi Keir,

On <20070412.172818.73333117.kuwa@jp.fujitsu.com>
 "KUWAMURA Shin''ya" wrote:
> 
>  - pygrub cannot access a domain more than 2^32 * SECTOR_SIZE because
>    get_fs_offset() treats the offset as a 32-bit integer. In GPT, the
>    offset must be treated as 64-bit integer.
> 
>  - This patch returns a part of a GUID unique to the partition as
>    legacy partition types. pygrub may misunderstand partition types.
I fixed these problems.

Best Regards,
-- 
  KUWAMURA Shin''ya


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