{{Short description|Memory map information provided by x86-based BIOS}} {{Lowercase title}} upright=1.2|thumb|Example of e820 information from dmesg '''e820''' is shorthand for the facility by which the BIOS of an x86-based computer system reports the memory map to the operating system or boot loader.<ref>{{cite web | url=https://uefi.org/sites/default/files/resources/ACPI_4_Errata_A.pdf | title=Advanced Configuration and Power Interface Specification | date=2010-04-05 | publisher=Unified Extensible Firmware Interface Forum | access-date=2020-03-11}}</ref>
It is accessed via the int 15h call, by setting the {{mono|AX}} register to value <code>E820</code> in hexadecimal. It reports which memory address ranges are usable and which are reserved for use by the BIOS.<ref>{{cite web | url=http://www.uruk.org/orig-grub/mem64mb.html | title=INT 15h, AX=E820h - Query System Address Map | author=Erich Boleyn | date=1996-07-02 | access-date=2020-03-11}}</ref>
BIOS-e820 is often the first thing reported by a booting Linux kernel, and it can also be seen with the dmesg command.
==References== <references/>
==External links== * [https://wiki.osdev.org/Detecting_Memory_(x86)#BIOS_Function:_INT_0x15.2C_EAX_.3D_0xE820 Detecting Memory (x86): BIOS Function: INT 0x15, EAX = 0xE820]
Category:BIOS
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