From 1963a0a6d7398a426d0701f90a5bc796e32899ae Mon Sep 17 00:00:00 2001
From: salmonik <salmonik@tuta.io>
Date: Fri, 31 Jul 2026 02:55:10 +0200
Subject: feat(rsboot): initial commit — UEFI bootloader extracted from RNG
MIME-Version: 1.0
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---
 main.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 main.c

(limited to 'main.c')

diff --git a/main.c b/main.c
new file mode 100644
index 0000000..d28a337
--- /dev/null
+++ b/main.c
@@ -0,0 +1,114 @@
+/* =============================================================================
+ * main.c — RNG UEFI bootloader (rsbl) — minimal smoke-test version
+ *
+ * Just prints to screen then loads kernel + initrd via LoadImage/StartImage.
+ * ============================================================================= */
+
+#include "uefi.h"
+
+static const char16 kpath[]   = u"\\bzImage";
+static const char16 ipath[]   = u"\\initramfs.cpio.gz";
+/* same cmdline systemd-boot used */
+static const char16 base_opt[] = u"console=ttyS0,115200 console=tty0 earlyprintk=serial,ttyS0,115200 loglevel=3 rng_tty=ttyS0 initrd=\\initramfs.cpio.gz";
+
+static efi_guid lg = EFI_LOADED_IMAGE_GUID;
+static efi_guid sg = EFI_SIMPLE_FILE_SYSTEM_GUID;
+
+static void pr(efi_simple_text_output *c, const char16 *s) { c->output_string(c, s); }
+static void ph(efi_simple_text_output *c, u64 v) {
+    char16 b[19] = u"0x0000000000000000";
+    for (int i = 17; i >= 2; i--) {
+        u8 n = (u8)(v & 0xF);
+        b[i] = n < 10 ? u'0' + n : u'a' + n - 10;
+        v >>= 4;
+    }
+    c->output_string(c, b);
+}
+
+static u64 allocate_pages(efi_boot_services *b, u64 mt, u64 np, u64 *a) {
+    typedef u64 (*F)(u64, u64, u64, u64 *);
+    return ((F)b->allocate_pages)(0, mt, np, a);
+}
+static u8 *rf(efi_boot_services *b, efi_file_protocol *f, u64 *sz, u64 mx) {
+    u64 np = (mx + 4095) / 4096, a;
+    if (allocate_pages(b, 6, np, &a)) return 0;
+    u8 *d = (u8 *)a;
+    u64 r = mx;
+    if (f->read(f, &r, d) && r != mx) return 0;
+    *sz = r; return d;
+}
+
+u64 __attribute__((aligned(16))) efi_main(handle ih, efi_system_table *st) {
+    efi_simple_text_output *c = st->con_out;
+    efi_boot_services      *b = st->boot_services;
+    u64 s;
+
+    pr(c, u"\r\n");
+    pr(c, u"rsbl v0.1 -- RNG UEFI Bootloader\r\n");
+    pr(c, u"\r\n");
+
+    efi_loaded_image *our_li;
+    s = b->handle_protocol(ih, &lg, (void **)&our_li);
+    if (s) { pr(c, u"  handle_protocol LI failed\r\n"); goto h; }
+
+    efi_simple_file_system *fs;
+    s = b->handle_protocol(our_li->device_handle, &sg, (void **)&fs);
+    if (s) { pr(c, u"  SFSP not on device handle\r\n"); goto h; }
+
+    efi_file_protocol *rt;
+    s = fs->open_volume(fs, (void **)&rt);
+    if (s) { pr(c, u"  open_volume failed\r\n"); goto h; }
+
+    pr(c, u"  [     loading kernel\r");
+    efi_file_protocol *f;
+    s = rt->open(rt, &f, (char16 *)kpath, 1, 0);
+    if (s) { pr(c, u"  [FAIL] loading kernel\r\n"); goto h; }
+    u64 ks; u8 *kd = rf(b, f, &ks, 64*1024*1024);
+    f->close(f);
+    if (!kd) { pr(c, u"  [FAIL] loading kernel\r\n"); goto h; }
+    pr(c, u"  [  ok] loading kernel  "); ph(c, ks); pr(c, u" bytes\r\n");
+
+    pr(c, u"  [     loading initrd\r");
+    s = rt->open(rt, &f, (char16 *)ipath, 1, 0);
+    if (s) { pr(c, u"  [FAIL] loading initrd\r\n"); goto h; }
+    u64 is; u8 *id = rf(b, f, &is, 32*1024*1024);
+    f->close(f);
+    if (!id) { pr(c, u"  [FAIL] loading initrd\r\n"); goto h; }
+    pr(c, u"  [  ok] loading initrd  "); ph(c, is); pr(c, u" bytes\r\n");
+
+    pr(c, u"  [     starting image\r");
+    handle kh = 0;
+    s = b->load_image(0, ih, 0, kd, ks, &kh);
+    if (s) { pr(c, u"  [FAIL] LoadImage\r\n"); goto h; }
+
+    efi_loaded_image *kli;
+    s = b->handle_protocol(kh, &lg, (void **)&kli);
+    if (s) { pr(c, u"  [FAIL] kernel image info\r\n"); goto h; }
+    kli->device_handle = our_li->device_handle;
+
+    u16 osz = 0;
+    while (base_opt[osz]) osz++;
+    osz = (osz + 1) * 2;
+    u16 *opts;
+    {
+        typedef u64 (*ap_t)(u8, u64, void **);
+        s = ((ap_t)b->allocate_pool)(0, osz, (void **)&opts);
+    }
+    if (s) { pr(c, u"  [FAIL] cmdline alloc\r\n"); goto h; }
+    for (u16 i = 0; i < osz / 2; i++) opts[i] = base_opt[i];
+    kli->load_options = opts;
+    kli->load_options_size = osz;
+
+    pr(c, u"  [  ok] starting image\r\n");
+    pr(c, u"\r\n");
+    pr(c, u"  Launching RNG/Linux ...\r\n");
+    pr(c, u"\r\n");
+
+    s = b->start_image(kh, 0, 0);
+    pr(c, u"  kernel returned "); ph(c, s); pr(c, u"\r\n");
+
+h:
+    pr(c, u"  Halt\r\n");
+    while (1) asm volatile("hlt");
+    return s;
+}
-- 
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