Fix disks: More than 2 drives?

[John B. Milton]

In article <1083 at icus.islp.ny.us> lenny at icus.islp.ny.us (Lenny Tropiano) writes:
>In article <1990Feb1.070641.17593 at stb.uucp> michael at stb.uucp (Michael Gersten) 
>writes:
>|>Here's a simple question: Did the fix disk hard disk driver allow
>|>using 4 drives (since there is hardware out there that supports it)?
>As per several e-mail messages from John Milton (jbm at uncle), I tried to
>get 4 drive support in the now released-UNIX3.51m.  No it's not there.
>Unfortunately there were several reasons why this couldn't be put in
>(or even snuck in).   Other problems like _risking_ possible other 
>bugs sneaking in by changing delicate device drivers (gd).  Again, since
>AT&T doesn't _officially_ support the two drive hack, they wouldn't go
>for a change like this for a four drive hack.   I certainly would have
>enjoyed seeing it if it became a reality!  I wouldn't mind having 
>three fixed hard drives, and a removable... dream on.
>
>What is the status on John's board?  Last I heard was Craig Votava saying
>he had problems with it?  Are you going to release the two-drive version of
>your pre-made PC board to the net? John?

Oh well, we tried. The code was actually VERY trivial.

As far as the HD2 project, I am satisfied with the performance so far.
Craig Votava is back up after several problems. The test machine I have
on loan from gws at n8emr ran until the power supply died.

I am now pricing various board building houses to get the HD2 board produced.
I have not changed the design at all, so if a 4 drive kernel ever comes out,
the board will still support it.

Since thing(s) like NMOUNT were changed, could someone please supply accurate
patches to the /usr/include/sys files? Lenny? John?

sys/gdisk.h: change DISKS from 3 to 6 /* two floppies (later) and four HDs */
sys/gdisk.h: change DRVMSK from 3 to 7 /* from two bits to three */
sys/hardware.h:	add DDRIVE2 0x0004
sys/hardware.h:	add DDRIVE3 0x0008
sys/space.h: add:
	char gdh2bbq[HDMAXCYL], gdh3bbq[HDMAXCYL];
	struct bbmcell gdh2bb[HDMAXBADBLK], gdh3bb[HDMAXBADBLK];
	two more structs: (ouch)
struct gdsw gdsw[] = {
	{	0,{"WIN2", 1023, 4, 17, 68,0, 0, 512},
		-1,0,16, 1023*16,40, ghdintr, ghdstart,
		HDMAXCYL, HDMAXBADBLK, gdh2bbq, gdh2bb,0},
	{	0,{"WIN3", 1023, 4, 17, 68,0, 0, 512},
		-1,0,16, 1023*16,40, ghdintr, ghdstart,
		HDMAXCYL, HDMAXBADBLK, gdh3bbq, gdh3bb,0}

struct iobuf	gdutab[DISKS];

I'll get to work on a loadable device driver that provides storage for the
additional arrays and new storage for the expandable arrays. Next, I need to
find all references to gdsw and gdutab so they can be patched at load time.
The last and yuckiest one is to find all the code to patched and patch it.
All this is an incredible bitch, but doable.

John
-- 
John Bly Milton IV, jbm at uncle.UUCP, n8emr!uncle!jbm at osu-cis.cis.ohio-state.edu
(614) h:252-8544, w:469-1990; N8KSN, AMPR: 44.70.0.52; Don't FLAME, inform!