[UNIKRAFT PATCH] arch: Provide cache line size KConfig option

[Alexander Jung <a.jung@xxxxxxxxxxx>]

This patch introduces `CONFIG_CACHE_LINE_SIZE` for statically
describing the CPU d-cache line size in bytes.

The d-cache line size can also be detected automatically at the
expense of using more memory and CPU cycles during boot time by
querying the `CPUID` instruction for `CLFLUSH`.

Signed-off-by: Alexander Jung <a.jung@xxxxxxxxxxx>
---
 arch/Config.uk | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/Config.uk b/arch/Config.uk
index 79097cf..3018518 100644
--- a/arch/Config.uk
+++ b/arch/Config.uk
@@ -33,3 +33,9 @@ config STACK_SIZE_PAGE_ORDER
                Indirectly configures the stack size by changing the stack size 
page
                order. Stack size is equal with 2^order * page size (e.g. 4KB).
                Only change this if you know what you're doing.
+
+config CACHE_LINE_SIZE
+       int "Cache line size"
+       default 32
+       help
+               Size in bytes of a CPU d-cache line.
-- 
2.11.0