On Mon, 20 Jan 2025 at 19:32, Sughosh Ganu sughosh.ganu@linaro.org wrote:
On Mon, 20 Jan 2025 at 18:01, Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 20.01.25 11:50, Sughosh Ganu wrote:
From: Masahisa Kojima kojima.masahisa@socionext.com
One of the problems OS installers face, when running in EFI, is that the mounted ISO after calling ExitBootServices goes away. For some distros this is a problem since they rely on finding some core packages before continuing the installation. Distros have works around this -- e.g Fedora has a special kernel command line parameter called inst.stage2 [0].
ACPI has NFIT and NVDIMM support to provide ramdisks to the OS, but we don't have anything in place for DTs. Linux and device trees have support for persistent memory devices. So add a function that can inject a pmem node in a DT, so we can use it when launhing OS installers with EFI.
We also have ACPI support in U-Boot. In a future patch series I guess we could add the generation of said ACPI tables.
[0] https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/ins...
Signed-off-by: Masahisa Kojima kojima.masahisa@socionext.com Signed-off-by: Sughosh Ganu sughosh.ganu@linaro.org
Changes since V2:
Fix a checkpatch error by putting a blank line after a function
boot/fdt_support.c | 40 +++++++++++++++++++++++++++++++++++++++- include/fdt_support.h | 13 +++++++++++++ 2 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/boot/fdt_support.c b/boot/fdt_support.c index 49efeec3681..613685b80eb 100644 --- a/boot/fdt_support.c +++ b/boot/fdt_support.c @@ -18,6 +18,7 @@ #include <dm/ofnode.h> #include <linux/ctype.h> #include <linux/types.h> +#include <linux/sizes.h> #include <asm/global_data.h> #include <asm/unaligned.h> #include <linux/libfdt.h> @@ -464,7 +465,6 @@ void do_fixup_by_compat_u32(void *fdt, const char *compat, do_fixup_by_compat(fdt, compat, prop, &tmp, 4, create); }
-#ifdef CONFIG_ARCH_FIXUP_FDT_MEMORY> /*
- fdt_pack_reg - pack address and size array into the "reg"-suitable stream
*/ @@ -493,6 +493,7 @@ static int fdt_pack_reg(const void *fdt, void *buf, u64 *address, u64 *size, return p - (char *)buf; }
+#ifdef CONFIG_ARCH_FIXUP_FDT_MEMORY
Do we need this #ifdef at all? We tend to leave it to the linker to eliminate functions.
This patch was authored by Kojima-san. I will have to check if we need to keep the ifdef.
I tried removing the ifdef from the said location. However, this causes a size increase on platforms where this config symbol is not enabled -- I tried this with the xilinx_zynqmp_virt_defconfig. This could be because the fdt_fixup_memory() function is included on all platforms as it gets called from cmd/fdt.c. The fdt_fixup_memory() function calls fdt_fixup_memory_banks() which is protected by this ifdef. Removing the ifdef then results in the fdt_fixup_memory_banks() getting included, instead of the empty stub resulting in the size increase.
-sughosh
#if CONFIG_NR_DRAM_BANKS > 4 #define MEMORY_BANKS_MAX CONFIG_NR_DRAM_BANKS #else @@ -2222,3 +2223,40 @@ int fdt_valid(struct fdt_header **blobp) } return 1; }
+int fdt_fixup_pmem_region(void *blob, ulong addr, u32 size) +{
u64 pmem_start[2] = { 0 };u64 pmem_size[2] = { 0 };char pmem_node[32] = {0};int nodeoffset, len;int err;u8 tmp[4 * 16]; /* Up to 64-bit address + 64-bit size */if (!IS_ALIGNED(addr, SZ_2M) || !IS_ALIGNED(addr + size, SZ_2M)) {printf("Start and end address needs at 2MB alignment\n");Nits:
%s/needs at 2MB alignment/must be 2 MiB aligned/
Will change
return -1;}snprintf(pmem_node, sizeof(pmem_node), "pmem@%lx", addr);nodeoffset = fdt_find_or_add_subnode(blob, 0, pmem_node);if (nodeoffset < 0)return nodeoffset;err = fdt_setprop_string(blob, nodeoffset, "compatible", "pmem-region");if (err)return err;err = fdt_setprop_empty(blob, nodeoffset, "volatile");if (err)return err;pmem_start[0] = addr;pmem_size[0] = size;len = fdt_pack_reg(blob, tmp, pmem_start, pmem_size, 1);err = fdt_setprop(blob, nodeoffset, "reg", tmp, len);if (err < 0) {printf("WARNING: could not set pmem %s %s.\n", "reg",fdt_strerror(err));return err;}return 0;+} diff --git a/include/fdt_support.h b/include/fdt_support.h index f0ad2e6b365..aea24df828f 100644 --- a/include/fdt_support.h +++ b/include/fdt_support.h @@ -507,4 +507,17 @@ void fdt_fixup_pstore(void *blob); */ int fdt_kaslrseed(void *blob, bool overwrite);
+/**
- fdt_fixup_pmem_region() - add a pmem node on the device tree
- This functions injects a pmem node to the device tree. Usually
- used with EFI installers to preserve installer images
If I understand the code correctly, the function adds or updates a pmem device-tree node for the given start address.
Will reword the comment.
-sughosh
Otherwise looks good to me.
Best regards
Heinrich
- @blob: device tree provided by caller
- @addr: start address of the pmem node
- @size: size of the memory of the pmem node
- Return: 0 on success or < 0 on failure
- */
+int fdt_fixup_pmem_region(void *blob, ulong addr, u32 size);
- #endif /* ifndef __FDT_SUPPORT_H */