On August 26, 2016 12:26:52 AM PDT, Eric Auer <e.a...@jpberlin.de> wrote:
>Hi HPA! The boot sector takes a BIOS drive number of the
>to-be-booted drive from the MBR, which can take it from
>the BIOS. There also are patches to take the MBR item by
>pointer from the MBR, but those are not used by default.
>So I guess the kernel could take the drive number from a
>boot sector, which at the moment is easy because the boot
>sector stores the value from the MBR in the drive byte of
>the boot sector loaded into RAM, which is a predictable
>location in general. Might be fun for booting from 0x81.
>>> support for EXT3 in the kernel would indeed be large/complex.
>Would not do that, but would boot DOS by MEMDISK and load a
>full EXT3 driver from there later :-) Same for ISO9660, but
>there "read files from ISO root dir" might be quite small,
>so boot without MEMDISK might be interesting as well...
>>> Regarding the idea to have the kernel "natively boot from a
>>> RAMDISK in HIGH MEMORY which would NOT be A: or C: ... Well,
>>> on modern computers it should not be a problem to "hog" the
>>> drive letter of the A: floppy drive - you probably have at
>>> most ONE real floppy next to that ramdisk anyway and letter
>>> B: is still free :-) So in that sense, MEMDISK is ok for me.
>Exactly :-)
>> So this is a horribly stale discussion, but it seems that all that is
>> needed is the ability to hide somewhere a preferred drive letter for
>> FreeDOS kernel to pick up and use.  It is trivial to add support for
>> passing such information along in MEMDISK.
>>      -hpa


Memdisk already supports being a disk number other than 0x00 or 0x80, and the 
DL register will reflect that.  However, I was thinking of provided a more 
explicit hint, so that scripts can reply on the ramdisk being, say, R:
Sent from my Android device with K-9 Mail. Please excuse brevity and formatting.

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