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Linux X86/x86_64 Will Now Always Reserve the First 1MB of RAM

posted by Fnord666 on Sunday June 06 2021, @05:51PM   Printer-friendly
from the 640k-is-more-memory-than-anyone-will-ever-need dept.

upstart writes in with an IRC submission for Runaway1956:

Linux x86/x86_64 Will Now Always Reserve The First 1MB Of RAM - Phoronix:

The Linux x86/x86_64 kernel code already had logic in place for reserving portions of the first 1MB of RAM to avoid the BIOS or kernel potentially clobbering that space among other reasons while now Linux 5.13 is doing away with that "wankery" and will just unconditionally always reserve the first 1MB of RAM.

[...] The motivation now for Linux 5.13 in getting that 1MB unconditional reservation in place for Linux x86/x86_64 stems from a bug report around an AMD Ryzen system being unbootable on Linux 5.13 since the change to consolidate their early memory reservations handling. Just unconditionally doing the first 1MB makes things much simpler to handle.

The change was sent in this morning as part of x86/urgent. "Do away with all the wankery of reserving X amount of memory in the first megabyte to prevent BIOS corrupting it and simply and unconditionally reserve the whole first megabyte."

no more wankery

Original Submission

 
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  • (Score: 3, Interesting) by Reziac on Monday June 07 2021, @03:10AM (2 children)

    by Reziac (2489) on Monday June 07 2021, @03:10AM (#1142613) Homepage

    LOL, yes, my 286 has one of those cards.... 2mb was at the time a massive upgrade, except DOS couldn't see it as system RAM (something was wrong with the card's driver). But it could see it as a RAMdisk. So I converted it into workspace, and had an astonishingly fast 286.

    --
    And there is no Alkibiades to come back and save us from ourselves.
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  • (Score: 2) by sjames on Monday June 07 2021, @12:23PM (1 child)

    by sjames (2882) on Monday June 07 2021, @12:23PM (#1142712) Journal

    That was the other crazy part. Until the 386 and 32 bit OSes, 1 MB was the limit for the old segmented memory without dirty tricks and poor performance, so the extra memory was bank switched into a 64K chunk of "high memory".

    • (Score: 2) by Reziac on Monday June 07 2021, @01:19PM

      by Reziac (2489) on Monday June 07 2021, @01:19PM (#1142723) Homepage

      This one was supposed to work as EMS, and did work on a different 286 and DOS5 (I ran DOS6). But not on mine, I already had RAM cram-packed with all my TSRs and everything worked out to the last byte, so not having it as usable RAM wasn't so bad. Having the high-speed workspace was more valuable, so I lost interest in pursuing it.

      --
      And there is no Alkibiades to come back and save us from ourselves.