🚀 go-pugleaf

After my article on the dangers of auto-reboot to disk caches, I
received the following piece of email, reposted with permission:

From georgef@microsoft.com (George Forsman)

Below is an acceptable version of a rebooter.  It makes a call to the
very useful, but very underused INT 15h, function 4fh.  This
particular call is trapped by a number (but I'm sure not all) disk
caches or anyone else who wants to clean up on reboot.

INT 15h, function 4Fh is a callout used by the INT 9 handler to let
someone else play with the scan code that it just grabbed from the
keyboard controller.  By poking in the CTRL+ALT shift flags, and then
issuing the INT 15h, you effectively simulate what the INT 9 handler
would be doing when you actually press the physical keys.

SMARTDRV v4.0 that is shipping with Windows 3.1 is a write-behind
cache, and it commits when the following code is run.  I have no idea
if hyperdisk, &c do the same.

0100   MOV      AX,0040
0103   MOV      DS,AX
0105   MOV      WORD PTR [0072],1234
010B   OR       WORD PTR [0017],000C
0111   MOV      AX,4F53
0114   INT      15
0116   JMP      F000:FFF0

If you wish to post this to the net, please do. I just don't feel
like arguing with vi tonight...
-- End of quoted message --

It's probably also a good idea to send out int 21/0d (disk reset) on
each disk drive as well as performing an INT 13 sector 0 read on
each hard drive.  Cache programs will probably listen to at least one of
these two operations and flush.

The Interrupt List also lists an int 2f/fe03 that Norton's NCACHE
listens to.