On Tue, Feb 7, 2012 at 9:51 AM, Tom Ehlert <t...@drivesnapshot.de> wrote:
> Dear PerditionC,
>    UBYTE DiskTransferBuffer[MAX_SEC_SIZE];
> wastes 3,5 KB low memory for *everybody*, not only when it's needed.
> regarding how much time we have spend until we had 640000 byte free
> I think this is a bad idea

please see my previous messages, I know exactly how much space is
wasted and clearly stated this along with statement 512 will be
default (and was already changed to such earlier)

> I also think that these experiments should NOT be in the stable
> branch.
> fork it, and make another 'unstable' branch if you want to experiment,
> but don't experiment with code that is supposed to be stable.
> Regards, Tom

These are not experiments, this is me working to improve compatibility
with MSDOS and existing though rare disks.  I purposely left a default
value larger than needed so I could track down a kernel issue with
memory allocation during initialization.  This issue still exists and
I believe may be one of the reasons  why there are occasional reports
of invalid opcode/crash during boot.

MSDOS sets the value based on known devices during startup, this is
documented in books describing it.  The FD kernel has been hardcoded
for 512 bytes.  My plan was first to ensure sizes > 512 bytes work
then make the changes to allow user to choose larger size than 512 so
only those who need the different value are penalized with increased
memory usage and can use FD kernel with their drive while everyone
else only has minimally larger kernel but more like MSDOS.  Part 1,
the changes so sizes >512 can be used was committed and uncovered a
memory allocation issue.  I put part 2 on hold because this seemed
important to find - instead I will leave the 512 hard coded which
rarely triggers the bug.

The experimental 4K build is based on my forked 0xdc (DOSC OEM id)
kernel, and it is where I do most of my changes before merging/testing
with the 0xfd kernel.


Keep Your Developer Skills Current with LearnDevNow!
The most comprehensive online learning library for Microsoft developers
is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3,
Metro Style Apps, more. Free future releases when you subscribe now!
Freedos-kernel mailing list

Reply via email to