Make a valiant, and probably futile, attempt to free memory aftersyslinux-1.65

running the PXE stack.

4 files changed, 194 insertions, 5 deletions

diff --git a/NEWS b/NEWS
index e55e28c5..e290fe8b 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,9 @@ Changes in 1.65:
 	  See memdisk/memdisk.doc for more info.
 	* PXELINUX, ISOLINUX: Correctly handle files larger than 65535
 	  blocks (32 MB for PXELINUX, 128 MB for ISOLINUX.)
+	* PXELINUX: Make a best-effort attempt at freeing all memory
+	  claimed.  From the looks of it, it will fail on most PXE
+	  stacks.
 
 Changes in 1.64:
 	* Limited support for hardware flow control when using a
diff --git a/memdisk/setup.c b/memdisk/setup.c
index e75bcb40..2ab5b98d 100644
--- a/memdisk/setup.c
+++ b/memdisk/setup.c
@@ -473,6 +473,9 @@ uint32_t setup(void)
   dosmem_k = rdz_16(BIOS_BASEMEM);
   pptr->olddosmem = dosmem_k;
   stddosmem = dosmem_k << 10;
+  /* If INT 15 E820 and INT 12 disagree, go with the most conservative */
+  if ( stddosmem > dos_mem )
+    stddosmem = dos_mem;
 
   pptr->driveno   = geometry->driveno;
   pptr->drivetype = geometry->type;
diff --git a/pxe.inc b/pxe.inc
index 31dbdcb8..0cbb72bc 100644
--- a/pxe.inc
+++ b/pxe.inc
@@ -56,4 +56,82 @@
 %define PXENV_RESTART_TFTP		0073h
 %define PXENV_MODE_SWITCH		0074h
 
+%define PXENV_EXIT_SUCCESS 0x0000 
+%define PXENV_EXIT_FAILURE 0x0001  
+
+%define PXENV_STATUS_SUCCESS 0x00 
+%define PXENV_STATUS_FAILURE 0x01  
+%define PXENV_STATUS_BAD_FUNC 0x02  
+%define PXENV_STATUS_UNSUPPORTED 0x03  
+%define PXENV_STATUS_KEEP_UNDI 0x04  
+%define PXENV_STATUS_KEEP_ALL 0x05 
+%define PXENV_STATUS_OUT_OF_RESOURCES 0x06  
+%define PXENV_STATUS_ARP_TIMEOUT 0x11  
+%define PXENV_STATUS_UDP_CLOSED 0x18 
+%define PXENV_STATUS_UDP_OPEN 0x19 
+%define PXENV_STATUS_TFTP_CLOSED 0x1A 
+%define PXENV_STATUS_TFTP_OPEN 0x1B  
+%define PXENV_STATUS_MCOPY_PROBLEM 0x20 
+%define PXENV_STATUS_BIS_INTEGRITY_FAILURE 0x21 
+%define PXENV_STATUS_BIS_VALIDATE_FAILURE 0x22 
+%define PXENV_STATUS_BIS_INIT_FAILURE 0x23 
+%define PXENV_STATUS_BIS_SHUTDOWN_FAILURE 0x24 
+%define PXENV_STATUS_BIS_GBOA_FAILURE 0x25 
+%define PXENV_STATUS_BIS_FREE_FAILURE 0x26 
+%define PXENV_STATUS_BIS_GSI_FAILURE 0x27 
+%define PXENV_STATUS_BIS_BAD_CKSUM 0x28  
+%define PXENV_STATUS_TFTP_CANNOT_ARP_ADDRESS 0x30 
+%define PXENV_STATUS_TFTP_OPEN_TIMEOUT 0x32
+
+%define PXENV_STATUS_TFTP_UNKNOWN_OPCODE 0x33 
+%define PXENV_STATUS_TFTP_READ_TIMEOUT 0x35 
+%define PXENV_STATUS_TFTP_ERROR_OPCODE 0x36 
+%define PXENV_STATUS_TFTP_CANNOT_OPEN_CONNECTION 0x38 
+%define PXENV_STATUS_TFTP_CANNOT_READ_FROM_CONNECTION 0x39 
+%define PXENV_STATUS_TFTP_TOO_MANY_PACKAGES 0x3A 
+%define PXENV_STATUS_TFTP_FILE_NOT_FOUND 0x3B 
+%define PXENV_STATUS_TFTP_ACCESS_VIOLATION 0x3C 
+%define PXENV_STATUS_TFTP_NO_MCAST_ADDRESS 0x3D 
+%define PXENV_STATUS_TFTP_NO_FILESIZE 0x3E 
+%define PXENV_STATUS_TFTP_INVALID_PACKET_SIZE 0x3F  
+%define PXENV_STATUS_DHCP_TIMEOUT 0x51 
+%define PXENV_STATUS_DHCP_NO_IP_ADDRESS 0x52 
+%define PXENV_STATUS_DHCP_NO_BOOTFILE_NAME 0x53 
+%define PXENV_STATUS_DHCP_BAD_IP_ADDRESS 0x54  
+%define PXENV_STATUS_UNDI_INVALID_FUNCTION 0x60 
+%define PXENV_STATUS_UNDI_MEDIATEST_FAILED 0x61 
+%define PXENV_STATUS_UNDI_CANNOT_INIT_NIC_FOR_MCAST 0x62 
+%define PXENV_STATUS_UNDI_CANNOT_INITIALIZE_NIC 0x63 
+%define PXENV_STATUS_UNDI_CANNOT_INITIALIZE_PHY 0x64 
+%define PXENV_STATUS_UNDI_CANNOT_READ_CONFIG_DATA 0x65 
+%define PXENV_STATUS_UNDI_CANNOT_READ_INIT_DATA 0x66 
+%define PXENV_STATUS_UNDI_BAD_MAC_ADDRESS 0x67 
+%define PXENV_STATUS_UNDI_BAD_EEPROM_CHECKSUM 0x68 
+%define PXENV_STATUS_UNDI_ERROR_SETTING_ISR 0x69 
+%define PXENV_STATUS_UNDI_INVALID_STATE 0x6A 
+%define PXENV_STATUS_UNDI_TRANSMIT_ERROR 0x6B 
+%define PXENV_STATUS_UNDI_INVALID_PARAMETER 0x6C  
+%define PXENV_STATUS_BSTRAP_PROMPT_MENU 0x74 
+%define PXENV_STATUS_BSTRAP_MCAST_ADDR 0x76 
+%define PXENV_STATUS_BSTRAP_MISSING_LIST 0x77 
+%define PXENV_STATUS_BSTRAP_NO_RESPONSE 0x78 
+%define PXENV_STATUS_BSTRAP_FILE_TOO_BIG 0x79  
+%define PXENV_STATUS_BINL_CANCELED_BY_KEYSTROKE 0xA0 
+%define PXENV_STATUS_BINL_NO_PXE_SERVER 0xA1 
+%define PXENV_STATUS_NOT_AVAILABLE_IN_PMODE 0xA2 
+%define PXENV_STATUS_NOT_AVAILABLE_IN_RMODE 0xA3  
+%define PXENV_STATUS_BUSD_DEVICE_NOT_SUPPORTED 0xB0  
+%define PXENV_STATUS_LOADER_NO_FREE_BASE_MEMORY 0xC0 
+%define PXENV_STATUS_LOADER_NO_BC_ROMID 0xC1 
+%define PXENV_STATUS_LOADER_BAD_BC_ROMID 0xC2 
+%define PXENV_STATUS_LOADER_BAD_BC_RUNTIME_IMAGE 0xC3 
+%define PXENV_STATUS_LOADER_NO_UNDI_ROMID 0xC4 
+%define PXENV_STATUS_LOADER_BAD_UNDI_ROMID 0xC5 
+%define PXENV_STATUS_LOADER_BAD_UNDI_DRIVER_IMAGE 0xC6 
+%define PXENV_STATUS_LOADER_NO_PXE_STRUCT 0xC8 
+%define PXENV_STATUS_LOADER_NO_PXENV_STRUCT 0xC9 
+%define PXENV_STATUS_LOADER_UNDI_START 0xCA 
+%define PXENV_STATUS_LOADER_BC_START 0xCB 
+
 %endif ; _PXE_INC
+
diff --git a/pxelinux.asm b/pxelinux.asm
index 4f5e806a..6df269e6 100644
--- a/pxelinux.asm
+++ b/pxelinux.asm
@@ -376,6 +376,7 @@ PktTimeout	resw 1			; Timeout for current packet
 KernelExtPtr	resw 1			; During search, final null pointer
 IPOptionLen	resw 1			; Length of IPOption
 LocalBootType	resw 1			; Local boot return code
+RealBaseMem	resw 1			; Amount of DOS memory after freeing
 TextAttrBX      equ $
 TextAttribute   resb 1			; Text attribute for message file
 TextPage        resb 1			; Active display page
@@ -476,7 +477,7 @@ _start1:
 
 		; Nothing there either.  Last-ditch: scan memory
 		call memory_scan_for_pxe_struct		; !PXE scan
-		jnc have_pxe
+		jnc near have_pxe
 		call memory_scan_for_pxenv_struct	; PXENV+ scan
 		jnc have_pxenv
 
@@ -500,12 +501,12 @@ have_pxenv:
 		mov ax,es
 		les bx,[es:bx+28h]		; !PXE structure pointer
 		cmp dword [es:bx],'!PXE'
-		je have_pxe
+		je near have_pxe
 
 		; Nope, !PXE structure missing despite API 2.1+, or at least
 		; the pointer is missing.  Do a last-ditch attempt to find it.
 		call memory_scan_for_pxe_struct
-		jnc have_pxe
+		jnc near have_pxe
 
 		; Otherwise, no dice, use PXENV+ structure
 		mov bx,si
@@ -518,6 +519,43 @@ old_api:	; Need to use a PXENV+ structure
 		mov eax,[es:bx+0Ah]		; PXE RM API
 		mov [PXENVEntry],eax
 
+		mov si,undi_data_msg		; ***
+		call writestr
+		mov ax,[es:bx+20h]
+		call writehex4
+		call crlf
+		mov si,undi_data_len_msg
+		call writestr
+		mov ax,[es:bx+22h]
+		call writehex4
+		call crlf
+		mov si,undi_code_msg
+		call writestr
+		mov ax,[es:bx+24h]
+		call writehex4
+		call crlf
+		mov si,undi_code_len_msg
+		call writestr
+		mov ax,[es:bx+26h]
+		call writehex4
+		call crlf
+
+		; Compute base memory size from PXENV+ structure
+		xor esi,esi
+		movzx eax,word [es:bx+20h]	; UNDI data seg
+		cmp ax,[es:bx+24h]		; UNDI code seg
+		ja .use_data
+		mov ax,[es:bx+24h]
+		mov si,[es:bx+26h]
+		jmp short .combine
+.use_data:
+		mov si,[es:bx+22h]
+.combine:
+		shl eax,4
+		add eax,esi
+		shr eax,10			; Convert to kilobytes
+		mov [RealBaseMem],ax
+
 		mov si,pxenventry_msg
 		call writestr
 		mov ax,[PXENVEntry+2]
@@ -527,12 +565,48 @@ old_api:	; Need to use a PXENV+ structure
 		mov ax,[PXENVEntry]
 		call writehex4
 		call crlf
-		jmp short have_entrypoint
+		jmp near have_entrypoint
 
 have_pxe:
 		mov eax,[es:bx+10h]
 		mov [PXEEntry],eax
 
+		mov si,undi_data_msg		; ***
+		call writestr
+		mov eax,[es:bx+2Ah]
+		call writehex8
+		call crlf
+		mov si,undi_data_len_msg
+		call writestr
+		mov ax,[es:bx+2Eh]
+		call writehex4
+		call crlf
+		mov si,undi_code_msg
+		call writestr
+		mov ax,[es:bx+32h]
+		call writehex8
+		call crlf
+		mov si,undi_code_len_msg
+		call writestr
+		mov ax,[es:bx+36h]
+		call writehex4
+		call crlf
+
+		; Compute base memory size from !PXE structure
+		xor esi,esi
+		mov eax,[es:bx+2Ah]
+		cmp eax,[es:bx+32h]
+		ja .use_data
+		mov eax,[es:bx+32h]
+		mov si,[es:bx+36h]
+		jmp short .combine
+.use_data:
+		mov si,[es:bx+2Eh]
+.combine:
+		add eax,esi
+		shr eax,10
+		mov [RealBaseMem],ax
+
 		mov si,pxeentry_msg
 		call writestr
 		mov ax,[PXEEntry+2]
@@ -4161,7 +4235,8 @@ ack_packet:
 ;
 ; unload_pxe:
 ;
-; This function unloads the PXE and UNDI stacks.
+; This function unloads the PXE and UNDI stacks and unclaims
+; the memory.
 ;
 unload_pxe:
 		mov di,pxe_udp_close_pkt
@@ -4173,7 +4248,32 @@ unload_pxe:
 		mov di,pxe_unload_stack_pkt
 		mov bx,PXENV_UNLOAD_STACK
 		call far [PXENVEntry]
+		jc .cant_free
+		cmp word [pxe_unload_stack_pkt.status],byte PXENV_STATUS_SUCCESS
+		jne .cant_free
+
+		mov ax,[RealBaseMem]
+		cmp ax,[BIOS_fbm]		; Sanity check
+		jna .cant_free
+
+		; Check that PXE actually unhooked the INT 1Ah chain
+		movzx ebx,word [4*0x1a]
+		movzx ecx,word [4*0x1a+2]
+		shl ecx,4
+		add ebx,ecx
+		shr ebx,10
+		cmp bx,ax			; Not in range
+		jae .ok
+		cmp bx,[BIOS_fbm]
+		jae .cant_free		
+
+.ok:
+		mov [BIOS_fbm],ax
 		ret
+		
+.cant_free:
+		mov si,cant_free_msg
+		jmp writestr
 
 ;
 ; gendotquad
@@ -4786,6 +4886,11 @@ pxeentry_msg	db 'PXE entry point found (we hope) at ', 0
 pxenventry_msg	db 'PXENV entry point found (we hope) at ', 0
 trymempxe_msg	db 'Scanning memory for !PXE structure... ', 0
 trymempxenv_msg	db 'Scanning memory for PXENV+ structure... ', 0
+undi_data_msg	  db 'UNDI data segment at:   ',0
+undi_data_len_msg db 'UNDI data segment size: ',0 
+undi_code_msg	  db 'UNDI code segment at:   ',0
+undi_code_len_msg db 'UNDI code segment size: ',0 
+cant_free_msg	db 'Failed to free base memory, sorry...', CR, LF, 0
 notfound_msg	db 'not found', CR, LF, 0
 myipaddr_msg	db 'My IP address seems to be ',0
 tftpprefix_msg	db 'TFTP prefix: ', 0