Re: Of removable devices

From: Khimenko Victor (khim@sch57.msk.ru)
Date: Wed Feb 16 2000 - 15:29:17 EST


In <Pine.GSO.4.10.10002161324530.13707-100000@weyl.math.psu.edu> Alexander Viro (viro@math.psu.edu) wrote:

> On Wed, 16 Feb 2000, David Balazic wrote:

>> AmigaOS just polled the line to detect insertions and removals.

> Wonderful. And how frequent the polling was?

It can be configure option :-) BTW it can do not very often. What's more
important is to check if there are disk changed before EVERY attempt to
write on disk. And VFS should be ready to get answer from device "device
POSSIBLE changed, please ask filesystem driver (floppy driver can do so
without filesystem since only filesystem knows where there are serial number
on floppy) to be shure". And when there can be more then one filesystem on
device (I can have fat and ext2fs floppies, fat/ext2fs/ntfs ZIP or
iso9660/ext2fs cd-rom :-) situation is even more interesting...

>> it would mount as another logical volume. Now when there was a need to
>> access
>> the first floppy, the OS popped up a dialog ( a requester, in amiga
>> terminology :-)
>> saying "Insert volume Linux_help_disk into any drive". When the user

> Ahem... OK, does anyone else see something strange in words "OS popped up
> a dialog"?

Of course Linux can not pop up a dialog :-) Only "OS" like AmigaOS or NT
where all stupid stuff is pushed in kernel can do this. Linux can block
request, send notification message to daemon (it'll be good to inform daemon
about process where such problem happened to not pop up 500 dialogs on
500 terminals on 5 different continents where all users connected to that
comp sits), this daemon open up dialog and wait for kernel to get message
"Ok, floppy found, you can remove your dialog". Perhaps daemon can notify
kernel as well when "Ok" in dialog clicked to try to search floppies in
different floppy drives (remember: I can have more then one floppy drive of
any type; situiation where you have both CD-ROM and CD-RW is not unusual,
for example). Gosh. PILE OF CHANGES ! Rowork of VFS, messages flying around,
daemons... Is it doable? Absolutely ! Is it worth it ? Perhaps not. But who
knows ?

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