USB boot

build/usb-boot-guide.md

@@ -0,0 +1,27 @@
+dd if=/dev/zero of=usbdisk.img bs=1M count=512
+echo 'start=2048, type=c' | sfdisk usbdisk.img
+LOOP=$(sudo losetup -f --show -P usbdisk.img)
+sudo mkfs.vfat -F 32 ${LOOP}p1
+sudo losetup -d $LOOP
+
+
+qemu-system-x86_64 -machine q35,accel=kvm -m 2G \
+  -boot d \
+  -cdrom ZealOS-PublicDomain-BIOS-2026-07-24-03_43_40.iso  \
+  -device qemu-xhci,id=xhci \
+  -drive if=none,id=ub,format=raw,file=usbdisk.img \
+  -device usb-storage,bus=xhci.0,drive=ub
+
+
+CopyTree("::/", "V:/");   # copies the whole CD to the stick — wait for it, takes a bit
+Dir("V:/");               # should now list Boot, Kernel, System, Compiler, Home, etc.
+BootHDIns('V');           # recompiles kernel on V: (few min), writes FAT32 boot record
+BootMHDIns('V');          # MBR chain-loader
+
+# At the BootHDIns config prompt, enter V for boot drive, ENTER through the rest.
+
+qemu-system-x86_64 -machine q35,accel=kvm -m 2G \
+  -device qemu-xhci,id=xhci \
+  -drive if=none,id=ub,format=raw,file=usbdisk.img \
+  -device usb-storage,bus=xhci.0,drive=ub \
+  -device usb-kbd,bus=xhci.0 -device usb-mouse,bus=xhci.0

src/Kernel/BlkDev/DiskAddDev.ZC

@@ -30,6 +30,29 @@ U0 BlkDevLockFwdingSet(CBlkDev *bd)
 	}
 }
 
+public Bool BlkDevRawBlksRead(CBlkDev *bd, U8 *buf, I64 blk, I64 count)
+{//Whole-device read, bypassing partition bounds. Dispatches on BlkDev type.
+//Used by $LK,"BlkDevAdd",A="MN:BlkDevAdd"$() partition scans and boot-loader installers.
+	if (bd->type == BDT_USB)
+	{
+		if (fp_usb_msd_blks_read)
+			return (*fp_usb_msd_blks_read)(bd, buf, blk, count);
+		return FALSE;
+	}
+	return AHCIAtaBlksRead(bd, buf, blk, count);
+}
+
+public Bool BlkDevRawBlksWrite(CBlkDev *bd, U8 *buf, I64 blk, I64 count)
+{//Whole-device write, bypassing partition bounds. Dispatches on BlkDev type.
+	if (bd->type == BDT_USB)
+	{
+		if (fp_usb_msd_blks_write)
+			return (*fp_usb_msd_blks_write)(bd, buf, blk, count);
+		return FALSE;
+	}
+	return AHCIAtaBlksWrite(bd, buf, blk, count);
+}
+
 I64 BlkDevAdd(CBlkDev *bd, I64 prt_num=I64_MIN, Bool whole_drive, Bool make_free)
 {//It will mount just one partition of prt_num>=0.
 //When repartitioing whole drive, whole_drive=TRUE.
@@ -68,6 +91,7 @@ I64 BlkDevAdd(CBlkDev *bd, I64 prt_num=I64_MIN, Bool whole_drive, Bool make_free
 			break;
 
 		case BDT_ATA:
+		case BDT_USB:
 			drive->drive_signature = DRIVE_SIGNATURE_VAL; //Temporarily validate
 			if (!BlkDevInit(bd))
 				drive->drive_signature = 0; //Revoke validation
@@ -83,14 +107,14 @@ I64 BlkDevAdd(CBlkDev *bd, I64 prt_num=I64_MIN, Bool whole_drive, Bool make_free
 					drive->size = bd->max_blk + 1 - bd->drv_offset;
 //The following read is a test read.
 					//if it hangs, the drive is not supported.
-					AHCIAtaBlksRead(bd, &mbr, 0, 1);
+					BlkDevRawBlksRead(bd, &mbr, 0, 1);
 					break;
 				}
 				offset = 0;
 				ext_base = INVALID_CLUS;
 				while (prt_num < 0 || num <= prt_num)
 				{
-					AHCIAtaBlksRead(bd, &mbr, offset, 1);
+					BlkDevRawBlksRead(bd, &mbr, offset, 1);
 					if (mbr.signature != 0xAA55)
 						break;
 					j = -1;
@@ -121,7 +145,7 @@ I64 BlkDevAdd(CBlkDev *bd, I64 prt_num=I64_MIN, Bool whole_drive, Bool make_free
 								case MBR_PT_FAT32d:
 								case MBR_PT_FAT32e:
 								case MBR_PT_FAT32f:
-									AHCIAtaBlksRead(bd, &br, drive->drv_offset, 1);
+									BlkDevRawBlksRead(bd, &br, drive->drv_offset, 1);
 
 									drive->drive_signature = DRIVE_SIGNATURE_VAL;
 									drive->prt_num = num;
@@ -238,21 +262,30 @@ U0 BlkDevsInitAll()
 	"\nAHCIInit;\n";
 	AHCIInit;
 
-	if (!blkdev.ahci_hba)
+	"\nUsbBootInit;\n";
+	i = UsbBootInit;
+
+	if (!blkdev.ahci_hba && !i)
 	{
-		"\nZealOS requires AHCI.\n\n"
+		"\nZealOS requires AHCI or a USB boot drive.\n\n"
 		"If in IDE compatibility mode, switch to SATA mode.\n"
 		"If running in a VM, ensure disks are organized under a SATA controller.\n\n"
 		"Rebooting in 10 seconds...\n";
 		Sleep(10*1000);
 		Reboot;
 	}
 
+//Config mount code may reference missing hardware (e.g. DVD-configured kernel
+//booted from a USB stick); failures fall through to UsbBootDriveFallback().
 	#exe {
+		StreamPrint("try {");
 		if (kernel_config->opts[CONFIG_MOUNT_AHCI_AUTO])
 			StreamPrint("MountAHCIAuto;");
 		StreamPrint("#exe {Option(OPTf_WARN_PAREN, OFF);}");
 		StreamDoc(kernel_config->add_dev);
 		StreamPrint("#exe {Option(OPTf_WARN_PAREN, ON);}");
+		StreamPrint("} catch { Fs->catch_except = TRUE; \"Boot mount code failed.\\n\"; }");
 	};
+
+	UsbBootDriveFallback;
 }

src/Kernel/BlkDev/DiskBlk.ZC

@@ -69,6 +69,13 @@ Bool BlkRead(CDrive *drive, U8 *buf, I64 blk, I64 count)
 				case BDT_ATAPI:
 					res = AHCIAtapiRBlks(drive, buf, blk, count);
 					break;
+
+				case BDT_USB:
+					if (fp_usb_msd_blks_read)
+						res = (*fp_usb_msd_blks_read)(bd, buf, blk, count);
+					else
+						res = FALSE;
+					break;
 			}
 			bd->last_time = tS;
 			if (bd->flags & BDF_READ_CACHE)
@@ -117,6 +124,13 @@ Bool BlkWrite(CDrive *drive, U8 *buf, I64 blk, I64 count)
 				case BDT_ATAPI:
 					res = AHCIAtaWBlks(drive, buf, blk, count);
 					break;
+
+				case BDT_USB:
+					if (fp_usb_msd_blks_write)
+						res = (*fp_usb_msd_blks_write)(bd, buf, blk, count);
+					else
+						res = FALSE;
+					break;
 			}
 			bd->last_time = tS;
 			if (bd->flags & BDF_READ_CACHE)

src/Kernel/BlkDev/DiskBlkDev.ZC

@@ -125,6 +125,13 @@ Bool BlkDevInit(CBlkDev *bd)
 				if (res = AHCIAtaInit(bd))
 					drive->size = bd->max_blk + 1;
 				break;
+
+			case BDT_USB:
+//USB mass storage driver fills in max_blk before BlkDevAdd().
+				bd->max_reads = 64;
+				bd->max_writes = 64;
+				res = TRUE;
+				break;
 		}
 		if (res && bd->flags & BDF_READ_CACHE)
 			DiskCacheInvalidate(drive);

src/Kernel/BlkDev/DiskDrive.ZC

@@ -202,8 +202,10 @@ I64 Letter2BlkDevType(U8 drv_let)
 		return BDT_ISO_FILE_READ;
 	if ('Q' <= drv_let <= 'S')
 		return BDT_ISO_FILE_WRITE;
-	if ('T' <= drv_let <= 'Z')
+	if ('T' <= drv_let <= 'U')
 		return BDT_ATAPI;
+	if ('V' <= drv_let <= 'Z')
+		return BDT_USB;
 
 	return BDT_NULL;
 }
@@ -347,7 +349,7 @@ U8 *DriveModelNum(U8 drv_let=0)
 	return res;
 }
 
-U8 blkdev_text_attr[BDT_TYPES_NUM]	= {BLACK, LTCYAN, WHITE, LTGREEN, LTRED, LTBLUE};
+U8 blkdev_text_attr[BDT_TYPES_NUM]	= {BLACK, LTCYAN, WHITE, LTGREEN, LTRED, LTBLUE, LTPURPLE};
 U8 drv_text_attr[3]					= {BLACK, BLUE, RED};
 
 U8 DriveTextAttrGet(U8 drv_let=0)

src/Kernel/BlkDev/DiskFormat.ZC

@@ -10,11 +10,12 @@ Bool DriveTypeSet(U8 drv_let, I64 type=FSt_REDSEA)
 	switch (bd->type)
 	{
 		case BDT_ATA:
+		case BDT_USB:
 			offset = 0;
 			ext_base = INVALID_CLUS;
 			while (TRUE)
 			{
-				AHCIAtaBlksRead(bd, &mbr, offset, 1);
+				BlkDevRawBlksRead(bd, &mbr, offset, 1);
 				j =- 1;
 				for (i = 0; i < 4; i++)
 				{
@@ -45,7 +46,7 @@ Bool DriveTypeSet(U8 drv_let, I64 type=FSt_REDSEA)
 										throw('Drive');
 								}
 								mbr.p[i].active = 0x80;
-								AHCIAtaBlksWrite(bd, &mbr, offset, 1);
+								BlkDevRawBlksWrite(bd, &mbr, offset, 1);
 								return TRUE;
 							}
 							drv_num++;

src/Kernel/KDefine.ZC

@@ -215,7 +215,8 @@ U0 SysDefinesLoad()
 						"ATA\0"
 						"FILE_READ\0"
 						"FILE_WRITE\0"
-						"ATAPI\0");
+						"ATAPI\0"
+						"USB\0");
 
 	DefineListLoad("ST_DRIVE_TYPES",
 						"NULL\0"

src/Kernel/KExterns.ZC

@@ -10,6 +10,8 @@ import Bool	 Ed(U8 *link_st=NULL, I64 edf_dof_flags=0);
 
 extern U0 SysErr(U8 *format, ...);
 extern U0 SysLog(U8 *format, ...);
+extern I64 UsbBootInit();
+extern U0 UsbBootDriveFallback();
 
 extern I64 MemBIOSTotal();
 

src/Kernel/KGlobals.ZC

@@ -33,6 +33,9 @@ CMouseHardStateGlobals	 mouse_hard, mouse_hard_last;
 CScreenCastGlobals		 screencast;
 CTextGlobals			 text;
 
+Bool	 (*fp_usb_msd_blks_read )(CBlkDev *bd, U8 *buf, I64 blk, I64 count); //Set by USB mass storage driver.
+Bool	 (*fp_usb_msd_blks_write)(CBlkDev *bd, U8 *buf, I64 blk, I64 count);
+
 U8		*(*fp_getstr2)(I64 flags=0);
 U0		 (*fp_update_ctrls)(CTask *task);
 CDoc	*(*fp_doc_put)(CTask *task=NULL);

src/Kernel/KMain.ZC

@@ -217,6 +217,8 @@ U0 KMain()
 	Spawn(&MouseHardDriverInstall);
 	"Spawn(&MouseRawWatcher,, \"MouseRawWatcher\");\n";
 	Spawn(&MouseRawWatcher,, "MouseRawWatcher");
+	"Spawn(&UsbTaskMain,, \"USB\");\n";
+	Spawn(&UsbTaskMain,, "USB");
 
 	"Load(\"Compiler\");\n";
 	Cd("/Compiler");

src/Kernel/Kernel.PRJ

@@ -55,6 +55,7 @@
 #include "MultiProc"
 #include "EdLite"
 #include "BlkDev/MakeBlkDev"
+#include "Usb/MakeKUsb"
 #include "FunSeg"
 #include "SMBIOS"
 #include "KMain"

src/Kernel/KernelA.HH

@@ -3319,7 +3319,8 @@ public class CDirEntry
 #define BDT_ISO_FILE_READ 		3
 #define BDT_ISO_FILE_WRITE		4
 #define BDT_ATAPI 				5
-#define BDT_TYPES_NUM 			6
+#define BDT_USB 				6
+#define BDT_TYPES_NUM 			7
 
 #define BDf_REMOVABLE 			0
 #define BDf_INITIALIZED 		1

src/Kernel/KernelC.HH

@@ -303,6 +303,8 @@ public extern	CBlkDev	*BlkDevCheck(CBlkDev *bd, Bool except=TRUE);
 public extern	U0		 BlkDevDel(  CBlkDev *bd);
 public extern	Bool	 BlkDevLock( CBlkDev *bd);
 public extern	CBlkDev	*BlkDevNextFreeSlot(U8 first_drive_let, I64 type);
+public extern	Bool	 (*fp_usb_msd_blks_read )(CBlkDev *bd, U8 *buf, I64 blk, I64 count);
+public extern	Bool	 (*fp_usb_msd_blks_write)(CBlkDev *bd, U8 *buf, I64 blk, I64 count);
 public extern	Bool	 BlkDevUnlock(CBlkDev *bd, Bool reset=FALSE);
 public extern	U0		 BlkDevsRelease();
 public extern	U0		 BlkDevRep();