• Bug#1105209: edk2: OVMF binaries built with debug memory clearing on fr

    From Luca Boccassi@21:1/5 to All on Tue May 13 14:40:01 2025
    Source: edk2
    Severity: wishlist

    Dear Maintainer(s),

    Current OVMF binaries for use with qemu (at least on x86_64) are built
    so that the debug function DebugClearMemory() runs and overwrites any
    pages being freed with BS->FreePages() with a fixed 0xAF pattern.

    Other than being most likely bad for performance, this recently also
    caused some headaches in shim when pages that were used to load images,
    and thus marked as non-writable and executable, were freed, which made
    OVMF attempt to overwrite them, which causes a crash due to non-
    writable attribute being set. For more details, see:

    https://github.com/rhboot/shim/pull/750

    As far as I can tell, this is caused by the 0x08 bit being set in gEfiMdePkgTokenSpaceGuid.PcdDebugPropertyMask in the OvmfPKgX64.dsc by
    default.

    Should the packages provide alternative debug binaries where these
    flags are enabled? Running this code is certainly useful for testing
    purposes, but I'm not sure for production usage. Separate debug-enabled binaries have been requested already in other bug reports, so maybe
    this flag could be enabled there, and removed from default builds?

    Thanks!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)