On Wed, Oct 24, 2018 at 02:55:17PM -0500, Rob Herring wrote:

On Wed, Oct 24, 2018 at 2:33 PM Florian Fainelli [off-list ref] wrote:

quoted

Hi all,

While investigating why ARM64 required a ton of objects to be rebuilt
when toggling CONFIG_DEV_BLK_INITRD, it became clear that this was
because we define __early_init_dt_declare_initrd() differently and we do
that in arch/arm64/include/asm/memory.h which gets included by a fair
amount of other header files, and translation units as well.

I scratch my head sometimes as to why some config options rebuild so
much stuff. One down, ? to go. :)

quoted

Changing the value of CONFIG_DEV_BLK_INITRD is a common thing with build
systems that generate two kernels: one with the initramfs and one
without. buildroot is one of these build systems, OpenWrt is also
another one that does this.

This patch series proposes adding an empty initrd.h to satisfy the need
for drivers/of/fdt.c to unconditionally include that file, and moves the
custom __early_init_dt_declare_initrd() definition away from
asm/memory.h

This cuts the number of objects rebuilds from 1920 down to 26, so a
factor 73 approximately.

Apologies for the long CC list, please let me know how you would go
about merging that and if another approach would be preferable, e.g:
introducing a CONFIG_ARCH_INITRD_BELOW_START_OK Kconfig option or
something like that.

There may be a better way as of 4.20 because bootmem is now gone and
only memblock is used. This should unify what each arch needs to do
with initrd early. We need the physical address early for memblock
reserving. Then later on we need the virtual address to access the
initrd. Perhaps we should just change initrd_start and initrd_end to
physical addresses (or add 2 new variables would be less invasive and
allow for different translation than __va()). The sanity checks and
memblock reserve could also perhaps be moved to a common location.

Alternatively, given arm64 is the only oddball, I'd be fine with an
"if (IS_ENABLED(CONFIG_ARM64))" condition in the default
__early_init_dt_declare_initrd as long as we have a path to removing
it like the above option.

I think arm64 does not have to redefine __early_init_dt_declare_initrd().
Something like this might be just all we need (completely untested,
probably it won't even compile):

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 9d9582c..e9ca238 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -62,6 +62,9 @@ s64 memstart_addr __ro_after_init = -1;
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
 #ifdef CONFIG_BLK_DEV_INITRD
+
+static phys_addr_t initrd_start_phys, initrd_end_phys;
+
 static int __init early_initrd(char *p)
 {
 	unsigned long start, size;

@@ -71,8 +74,8 @@ static int __init early_initrd(char *p)
 	if (*endp == ',') {
 		size = memparse(endp + 1, NULL);
 
-		initrd_start = start;
-		initrd_end = start + size;
+		initrd_start_phys = start;
+		initrd_end_phys = end;
 	}
 	return 0;
 }

@@ -407,14 +410,27 @@ void __init arm64_memblock_init(void)
 		memblock_add(__pa_symbol(_text), (u64)(_end - _text));
 	}
 
-	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
+	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) &&
+	    (initrd_start || initrd_start_phys)) {
+		/*
+		 * FIXME: ensure proper precendence between
+		 * early_initrd and DT when both are present
+		 */
+		if (initrd_start) {
+			initrd_start_phys = __phys_to_virt(initrd_start);
+			initrd_end_phys = __phys_to_virt(initrd_end);
+		} else if (initrd_start_phys) {
+			initrd_start = __va(initrd_start_phys);
+			initrd_end = __va(initrd_start_phys);
+		}
+
 		/*
 		 * Add back the memory we just removed if it results in the
 		 * initrd to become inaccessible via the linear mapping.
 		 * Otherwise, this is a no-op
 		 */
-		u64 base = initrd_start & PAGE_MASK;
-		u64 size = PAGE_ALIGN(initrd_end) - base;
+		u64 base = initrd_start_phys & PAGE_MASK;
+		u64 size = PAGE_ALIGN(initrd_end_phys) - base;
 
 		/*
 		 * We can only add back the initrd memory if we don't end up

@@ -458,7 +474,7 @@ void __init arm64_memblock_init(void)
 	 * pagetables with memblock.
 	 */
 	memblock_reserve(__pa_symbol(_text), _end - _text);
-#ifdef CONFIG_BLK_DEV_INITRD
+#if 0
 	if (initrd_start) {
 		memblock_reserve(initrd_start, initrd_end - initrd_start);
 
 

Rob

-- 
Sincerely yours,
Mike.