On 2017-02-06 22:10, Paul Koning wrote:
On Feb 5, 2017, at 6:25 PM, Paul Koning <[email protected]> wrote:
On Feb 5, 2017, at 3:31 PM, Mark Pizzolato <[email protected]> wrote:
...
So, I'd like to expand the set of file system types that the auto sizing logic
can perform
to include RSTS disks and whatever might be commonly used with RSX and RT11.
A possible complication with RSTS: I can't find the precise device size because
that isn't stored anywhere in the file structure. What I can find is the size
rounded up to the next multiple of 4096 times the cluster size (from the free
space bitmap size in blocks, since each bit represents a free cluster). I can
also find a lower bound, from the end of the last free cluster in the bitmap.
But if some of the space at the end of the pack is in use -- not all that
common but certainly possible -- then that doesn't help.
So if given a table of possible sizes for the controller model in question,
this is certainly doable. If two possible devices have sizes that are close it
wouldn't always be possible to get the right answer. Real disks are probably
ok, but MSCP disks with user-selected sizes not corresponding to actual DEC
models are likely to be a problem.
Does the autosize routine have access to the controller model designation?
I suspect the need is mostly to determine when the code should give an
error that you are accessing blocks outside the disk. If the actual
image file was not preallocated to the correct size, you face a dilemma
in simh. Access beyond current eof may, or may not be legitimate.
I would say that your upper bound calculation is good enough. A small
rounding error giving a few extra blocks are probably ok.
This is done for MSCP and Massbus disks. So I don't think controller
model identifications help.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: [email protected] || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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