Re: writable mmc profiles actually are writable

Pat LaVarre
2003-10-06T19:50:41Z

> assuming this has to do with misdetected hardware?

Seemingly so, aye.

> hardware?

I'm plugging in a pre-production sample of a new device.

Seemingly I cannot mkudffs its disks except by patching the kernel.

That's normal for yet another new kind of dvd/cd, yes?

Via sg I see 35 GB of 64 KiB/block writes, 2 KiB/block reads, with
writable profile x0002 removable_disk of the 1999 mmc 2 standard. Yes
pdt x05 dvd/cd, yes feature x0020 random_writable, no not the cd_r,
cd_rw, dvd, dvd_r, and dvd_ram enumerated in the obsolete legacy 1997
mmc 1 mode page x2A Capabilities.

Previously near here we discussed some as-yet-ineffective alternatives
to my patch: the Andy Polyakov patch for mount -w of dvd+rw, the Jens
Axboe patch for mount -w of cd-rw, and blockdev --setrw.

> The uniform layer uses CDC_DVD_RAM as meaning
> randomly writable media,

When I try setting CDC_DVD_RAM for a device, I see
/proc/sys/dev/cdrom/info erroneously reports:

Can write DVD-RAM: 1

I conclude we wish to express the discovery of feature x0020
random_writable differently. Wrong?

In weak confirmation, earlier I did see the usb-storage folk reject a
patch to tweak mode page x2A to appear to have mode page x2A byte 3 mask
x20 dvd_ram_write set. Should I submit a patch like that for sr_mod.ko
and ide-cd.ko?

> Calling read-only media failing to be opened
> read-write as "uncooperative" is confusing,

Clear now? I mean to say, sg_dd shows the real disk of the real device
is randomly rewritable. But cdrom.ko and sr_mod.ko refuse to pass
writes thru.

> screws threading of decent mailers

Sorry. I'm pleased to mention people have kindly volunteered offline to
help me avoid repeating that.

Pat LaVarre