CONFIG_X86_RESERVE_LOW: Amount of low memory, in kilobytes, to reserve for the BIOS

General informations

The Linux kernel configuration item CONFIG_X86_RESERVE_LOW:

• prompt: Amount of low memory, in kilobytes, to reserve for the BIOS
• type: int
• depends on: (none)
• defined in arch/x86/Kconfig
• found in Linux kernels: 2.6.37–2.6.39, 3.0–3.19, 4.0–4.20, 5.0–5.13

Help text

Specify the amount of low memory to reserve for the BIOS.

The first page contains BIOS data structures that the kernel must not use, so that page must always be reserved.

By default we reserve the first 64K of physical RAM, as a number of BIOSes are known to corrupt that memory range during events such as suspend/resume or monitor cable insertion, so it must not be used by the kernel.

You can set this to 4 if you are absolutely sure that you trust the BIOS to get all its memory reservations and usages right. If you know your BIOS have problems beyond the default 64K area, you can set this to 640 to avoid using the entire low memory range.

If you have doubts about the BIOS (e.g. suspend/resume does not work or there's kernel crashes after certain hardware hotplug events) then you might want to enable X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical corruption patterns.

Leave this to the default value of 64 if you are unsure.

Hardware

LKDDb

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Sources

This page is automaticly generated with free (libre, open) software lkddb(see lkddb-sources).

The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

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