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> Helpfully Linux does not appear to clobber DOS’s memory during its own boot process.

Is that just a coincidence or intentional somehow?

I guess DOS can only access the first 1MB (err... plus 65520 HMA bytes?), so if Linux just avoids using that space then DOS can keep running happily... I was curious if there's actually a mechanism to tell Linux to avoid that space.

DOS memory management fascinates me in its absurdity.

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With HIMEM.SYS + EMM386.EXE [0][1], you could include or exclude certain memory segments. But, DOS Subsystem for Linux uses non-standard little documented Unreal Mode [2][3] instead of traditional DOS Memory Management.

[0] http://www.mdgx.com/mem6.htm#6

[1] http://manmrk.net/tutorials/DOS/msdos7/emm386.htm

[2] https://en.m.wikipedia.org/wiki/Unreal_mode

[3] https://github.com/charliesome/doslinux/blob/master/doslinux...

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