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On-disk File Timestamps

The Single Unix Specification, Base Definitions (XBD), Section 4.8 entitled “File Times Update” states “An implementation may update timestamps that are marked for update immediately, or it may update such timestamps periodically.” This means that, for example, that file read and write operations are free to set the appropriate flags in the in-memory structures and do the actual updating of the on-disk filesystem structures at a later time. Assuming periodically means from time to time, it implies that a POSIX-compliant operating system is free to update it’s on-disk structures when it is convenient for the operating system to do so.

Access BGRT Information and Boot Graphics From UEFI Shell

In this post, I provide the source code for a small UEFI shell utility which will display information about a ACPI 5.0 BGRT table, if present, and allow you to save the referenced boot logo as a BMP file.