[comp.os.minix] Huge cache under Minix-32

andrew@eleceng.bradford.ac.uk (Andrew G. Minter) (09/28/90)

I'm using Bruce Evan's 32-bit Minix and booting with shoelace.

After upgrading my RAM to 4Mb, I tried increasing the size of the cache to
1Mb, but now shoelace locks up whebn trying to load the fs.

Does anyone out there have any idea what might be wrong?

Cheers, Andrew
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brucee@runxtsa.runx.oz.au (Bruce Evans) (09/30/90)

In article <31783@nigel.ee.udel.edu> andrew@eleceng.bradford.ac.uk (Andrew G. Minter) writes:
>After upgrading my RAM to 4Mb, I tried increasing the size of the cache to
>1Mb, but now shoelace locks up whebn trying to load the fs.

The cache has to fit below 640K because the system is loaded into the
real-mode address space :(. Shoelace should detect that the big FS would
overwrite shoelace and abort the boot. However, the check for this has a
bug. It fails for small overwrites. I'm not sure what happens for large
ones.
-- 
Bruce Evans  (evans@syd.dit.csiro.au)

hays@isc.intel.com (Kirk Hays) (10/06/90)

In article <2324@runxtsa.runx.oz.au> brucee@runxtsa.runx.oz.au (Bruce Evans) writes:
|In article <31783@nigel.ee.udel.edu> andrew@eleceng.bradford.ac.uk (Andrew G. Minter) writes:
|>After upgrading my RAM to 4Mb, I tried increasing the size of the cache to
|>1Mb, but now shoelace locks up whebn trying to load the fs.
|
|The cache has to fit below 640K because the system is loaded into the
|real-mode address space :(. Shoelace should detect that the big FS would
|overwrite shoelace and abort the boot. However, the check for this has a
|bug. It fails for small overwrites. I'm not sure what happens for large
|ones.
|-- 
|Bruce Evans  (evans@syd.dit.csiro.au)

Sounds like time for a two stage boot:

	1.  boot a "small" 386 minix using shoelace
	2.  run a protected mode shoelace that runs in the
	    low 640K of memory, loading the "big" 386 minix
	    into high RAM.


-- 
Kirk Hays - NRA Life.  Dulce et Decorum est, pro patra mori.
"The way of the samurai is found in death.  It is this simple.  If you
 can accept it then you will fight as though you are already dead."
Tsunemoto Yamamoto, _Hagakure_

MDOELL%DOSUNI1.BITNET@cunyvm.cuny.edu (Magnus Doell) (10/08/90)

Couldn't we avoid the cache to be build into the image?
As we have vm with the 386, why don't use it to fill the memory
used by FS' cache during initialization?
If we make the initialization a little bit trickier, we could avoid
to build in nearly all the bss by just copying the data regions a
little bit.
By the way, I had read about a project with a 2-stage FS-cache a while
ago (I guess they wanted the second cache dynamically allocated outside
FS' address space). What's about this?
All this makes the image a little bit smaller, the loading a little bit
faster and the initialization a little bit trickier and slower (but you
can copy a lot of memory before reading one sector :-).

Ma.D.