Many distros are shipping raw kernel images (i.e. vmlinux.efi).

Support booting such image by parsing header as per Linux's
specification [1].

[1]: https://docs.kernel.org/arch/loongarch/booting.html

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
It is based on my previous booting protocol patch
---
 hw/loongarch/boot.c         | 45 +++++++++++++++++++++++++++++++++++++++++++++
 include/hw/loongarch/boot.h | 17 +++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/hw/loongarch/boot.c b/hw/loongarch/boot.c
index 93847b0eaf8e50ce1a990b91267780e6785e1c2f..5bc889c51fafa9c6d37426b9bee9709c12183927 100644
--- a/hw/loongarch/boot.c
+++ b/hw/loongarch/boot.c
@@ -260,6 +260,43 @@ static uint64_t cpu_loongarch_virt_to_phys(void *opaque, uint64_t addr)
     return addr & MAKE_64BIT_MASK(0, TARGET_PHYS_ADDR_SPACE_BITS);
 }
 
+static int64_t get_linux_image_info(struct loongarch_boot_info *info,
+                                    uint64_t *kernel_entry,
+                                    uint64_t *kernel_low,
+                                    uint64_t *kernel_high)
+{
+    int fd;
+    struct loongarch_linux_hdr hdr;
+    int64_t kernel_size = -1;
+
+    fd = open(info->kernel_filename, O_RDONLY | O_BINARY);
+    if (fd < 0) {
+        return -1;
+    }
+
+    if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) {
+        close(fd);
+        return -1;
+    }
+
+    if ((le32_to_cpu(hdr.mz_magic) & 0xffff) != MZ_MAGIC ||
+        le32_to_cpu(hdr.linux_pe_magic) != LINUX_PE_MAGIC) {
+        close(fd);
+        return -1;
+    }
+
+    *kernel_entry = le64_to_cpu(hdr.kernel_entry);
+    /* Early kernel versions may have those fields in virtual address */
+    *kernel_entry &= MAKE_64BIT_MASK(0, TARGET_PHYS_ADDR_SPACE_BITS);
+    *kernel_low = le64_to_cpu(hdr.load_offset);
+    *kernel_low &= MAKE_64BIT_MASK(0, TARGET_PHYS_ADDR_SPACE_BITS);
+    kernel_size = le64_to_cpu(hdr.kernel_size);
+    *kernel_high = *kernel_low + kernel_size;
+
+    close(fd);
+    return kernel_size;
+}
+
 static int64_t load_kernel_info(struct loongarch_boot_info *info)
 {
     uint64_t kernel_entry, kernel_low, kernel_high;
@@ -270,6 +307,14 @@ static int64_t load_kernel_info(struct loongarch_boot_info *info)
                            &kernel_entry, &kernel_low,
                            &kernel_high, NULL, 0,
                            EM_LOONGARCH, 1, 0);
+    if (kernel_size < 0) {
+        kernel_size = get_linux_image_info(info, &kernel_entry,
+                                           &kernel_low, &kernel_high);
+        if (kernel_size >= 0) {
+            kernel_size = load_image_targphys(info->kernel_filename,
+                                              kernel_low, kernel_size);
+        }
+    }
 
     if (kernel_size < 0) {
         error_report("could not load kernel '%s': %s",
diff --git a/include/hw/loongarch/boot.h b/include/hw/loongarch/boot.h
index 96ec15016a314499acf65c6c47e0c4932aa99d01..5e8bd4dd73bbb27abccfa1fa577df52aed15b6a2 100644
--- a/include/hw/loongarch/boot.h
+++ b/include/hw/loongarch/boot.h
@@ -8,6 +8,23 @@
 #ifndef HW_LOONGARCH_BOOT_H
 #define HW_LOONGARCH_BOOT_H
 
+/* Linux Image Format */
+#define LINUX_PE_MAGIC  0x818223cd
+#define MZ_MAGIC        0x5a4d /* "MZ" */
+
+struct loongarch_linux_hdr {
+    uint32_t mz_magic;
+    uint32_t res0;
+    uint64_t kernel_entry;
+    uint64_t kernel_size;
+    uint64_t load_offset;
+    uint64_t res1;
+    uint64_t res2;
+    uint64_t res3;
+    uint32_t linux_pe_magic;
+    uint32_t pe_header_offset;
+} QEMU_PACKED;
+
 /* UEFI 2.10 */
 #define EFI_SYSTEM_TABLE_SIGNATURE       0x5453595320494249
 #define EFI_2_100_SYSTEM_TABLE_REVISION  ((2<<16) | (100))

---
base-commit: c69612063e1844b76ac01e3a781b979548c3585c
change-id: 20241222-la-direct-kernel-boot-c598264710e7

Best regards,
-- 
Jiaxun Yang <jiaxun.yang@flygoat.com>