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-rw-r--r--lib/Kconfig.debug23
1 files changed, 20 insertions, 3 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 289dfcbc14eb..073496dea848 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1869,9 +1869,26 @@ config STRICT_DEVMEM
enabled, even in this case there are restrictions on /dev/mem
use due to the cache aliasing requirements.
+ If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
+ file only allows userspace access to PCI space and the BIOS code and
+ data regions. This is sufficient for dosemu and X and all common
+ users of /dev/mem.
+
+ If in doubt, say Y.
+
+config IO_STRICT_DEVMEM
+ bool "Filter I/O access to /dev/mem"
+ depends on STRICT_DEVMEM
+ default STRICT_DEVMEM
+ ---help---
+ If this option is disabled, you allow userspace (root) access to all
+ io-memory regardless of whether a driver is actively using that
+ range. Accidental access to this is obviously disastrous, but
+ specific access can be used by people debugging kernel drivers.
+
If this option is switched on, the /dev/mem file only allows
- userspace access to PCI space and the BIOS code and data regions.
- This is sufficient for dosemu and X and all common users of
- /dev/mem.
+ userspace access to *idle* io-memory ranges (see /proc/iomem) This
+ may break traditional users of /dev/mem (dosemu, legacy X, etc...)
+ if the driver using a given range cannot be disabled.
If in doubt, say Y.