[haiku-bugs] Re: [Haiku] #6036: Read from cd failure (ISO9660 haiku-r1-alpha2.iso)
- From: "axeld" <trac@xxxxxxxxxxxx>
- Date: Tue, 01 Jun 2010 10:10:41 -0000
#6036: Read from cd failure (ISO9660 haiku-r1-alpha2.iso)
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Reporter: aldeck | Owner: mmlr
Type: bug | Status: assigned
Priority: normal | Milestone: R1
Component: Drivers/Disk | Version: R1/alpha2
Keywords: | Platform: All
Blockedby: | Patch: 0
Blocking: |
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Comment(by axeld):
I just looked into the issue: according to the linux sources, the SCSI
spec allows the device to report up to 75 blocks beyond its actual size.
While I did not find any mention of this in the specs (only looked at
MMC-5/READ_CAPACITY), what they do is to check whether an access covered
the last part of a device, and adjust the disk size on the fly then by
evaluating the exact SCSI reply (see drivers/scsi/sr.c::sr_done() line
257ff in 2.6.34). FreeBSD ignores the issue, so it should have the same
issues we have.
As a possible work-around, I would suggest issuing an additional read in
cd_set_capacity(), and handling the error case in either periph_io(), or
adding a dedicated function for this in scsi_cd (I would prefer the
latter).
--
Ticket URL: <http://dev.haiku-os.org/ticket/6036#comment:4>
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