Date: Wed, 22 Jun 2011 13:33:01 -0400 From: John Baldwin <jhb@freebsd.org> To: Henri Hennebert <hlh@restart.be> Cc: freebsd-stable@freebsd.org Subject: Re: ZFS boot inside on the second partition inside a slice Message-ID: <201106221333.01437.jhb@freebsd.org> In-Reply-To: <4E021CEB.4080703@restart.be> References: <BANLkTi=drd8vY84_4jqDZTFK%2Bsq=n0Kx9g@mail.gmail.com> <201106221158.16485.jhb@freebsd.org> <4E021CEB.4080703@restart.be>
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On Wednesday, June 22, 2011 12:48:43 pm Henri Hennebert wrote: > No error message but a reboot... > > I add: > > loop main.6 # If not last, read another > > mov $msg_debug,%si > call putstr > > mov $MEM_BTX,%si # BTX > > ...... > > msg_debug: .asciz "@\r\n" > > I don't get the @ on the console :-( Hmm, so it never exits the loop? > PS - I have to keep a short message otherwise: > > /usr/src/sys/boot/i386/zfsboot/zfsldr.S:322: Error: attempt to move .org > backwards Yeah, it's getting tight. I've commented the LBA printing bits out (so there is more room to play with) and made it print out a "." for each disk sector read: Index: zfsldr.S =================================================================== --- zfsldr.S (revision 223365) +++ zfsldr.S (working copy) @@ -16,7 +16,6 @@ */ /* Memory Locations */ - .set MEM_REL,0x700 # Relocation address .set MEM_ARG,0x900 # Arguments .set MEM_ORG,0x7c00 # Origin .set MEM_BUF,0x8000 # Load area @@ -91,26 +90,18 @@ main: cld # String ops inc mov %cx,%ss # Set up mov $start,%sp # stack /* - * Relocate ourself to MEM_REL. Since %cx == 0, the inc %ch sets - * %cx == 0x100. - */ - mov %sp,%si # Source - mov $MEM_REL,%di # Destination - incb %ch # Word count - rep # Copy - movsw # code -/* * If we are on a hard drive, then load the MBR and look for the first * FreeBSD slice. We use the fake partition entry below that points to * the MBR when we call nread. The first pass looks for the first active * FreeBSD slice. The second pass looks for the first non-active FreeBSD * slice if the first one fails. */ - mov $part4,%si # Partition + mov $part4,%si # Dummy partition cmpb $0x80,%dl # Hard drive? jb main.4 # No - movb $0x1,%dh # Block count - callw nread # Read MBR + xor %eax,%eax # Read MBR + movw $MEM_BUF,%bx # from first + callw nread # sector mov $0x1,%cx # Two passes main.1: mov $MEM_BUF+PRT_OFF,%si # Partition table movb $0x1,%dh # Partition @@ -143,32 +134,35 @@ main.4: xor %dx,%dx # Partition:drive * (i.e. after the two vdev labels). We don't have do anything fancy * here to allow for an extra copy of boot1 and a partition table * (compare to this section of the UFS bootstrap) so we just load it - * all at 0x8000. The first part of boot2 is BTX, which wants to run + * all at 0x9000. The first part of boot2 is BTX, which wants to run * at 0x9000. The boot2.bin binary starts right after the end of BTX, * so we have to figure out where the start of it is and then move the - * binary to 0xc000. After we have moved the client, we relocate BTX - * itself to 0x9000 - doing it in this order means that none of the - * memcpy regions overlap which would corrupt the copy. Normally, BTX - * clients start at MEM_USR, or 0xa000, but when we use btxld to - * create zfsboot2, we use an entry point of 0x2000. That entry point is - * relative to MEM_USR; thus boot2.bin starts at 0xc000. + * binary to 0xc000. Normally, BTX clients start at MEM_USR, or 0xa000, + * but when we use btxld to create zfsboot2, we use an entry point of + * 0x2000. That entry point is relative to MEM_USR; thus boot2.bin + * starts at 0xc000. * * The load area and the target area for the client overlap so we have * to use a decrementing string move. We also play segment register * games with the destination address for the move so that the client * can be larger than 16k (which would overflow the zero segment since - * the client starts at 0xc000). Relocating BTX is easy since the load - * area and target area do not overlap. + * the client starts at 0xc000). */ main.5: mov %dx,MEM_ARG # Save args - movb $NSECT,%dh # Sector count + mov $NSECT,%cx # Sector count movl $1024,%eax # Offset to boot2 - callw nread.1 # Read disk -main.6: mov $MEM_BUF,%si # BTX (before reloc) + mov $MEM_BTX,%bx # Destination buffer +main.6: pushal # Save params + callw nread # Read disk + popal # Restore + incl %eax # Update for + add $SIZ_SEC,%bx # next sector + loop main.6 # If not last, read another + mov $MEM_BTX,%si # BTX mov 0xa(%si),%bx # Get BTX length and set mov $NSECT*SIZ_SEC-1,%di # Size of load area (less one) mov %di,%si # End of load - add $MEM_BUF,%si # area + add $MEM_BTX,%si # area sub %bx,%di # End of client, 0xc000 rel mov %di,%cx # Size of inc %cx # client @@ -179,12 +173,6 @@ main.5: mov %dx,MEM_ARG # Save args movsb # client mov %ds,%dx # Back to mov %dx,%es # zero segment - mov $MEM_BUF,%si # BTX (before reloc) - mov $MEM_BTX,%di # BTX - mov %bx,%cx # Get BTX length - cld # Increment this time - rep # Relocate - movsb # BTX /* * Enable A20 so we can access memory above 1 meg. @@ -214,30 +202,40 @@ seta20.3: sti # Enable interrupts * packet on the stack and passes it to read. * * %eax - int - LBA to read in relative to partition start + * %es:%bx - ptr - destination address * %dl - byte - drive to read from - * %dh - byte - num sectors to read * %si - ptr - MBR partition entry */ -nread: xor %eax,%eax # Sector offset in partition -nread.1: xor %ecx,%ecx # Get +nread: xor %ecx,%ecx # Get addl 0x8(%si),%eax # LBA adc $0,%ecx pushl %ecx # Starting absolute block pushl %eax # block number push %es # Address of - push $MEM_BUF # transfer buffer - xor %ax,%ax # Number of - movb %dh,%al # blocks to - push %ax # transfer + push %bx # transfer buffer + push $0x1 # Read 1 sector push $0x10 # Size of packet mov %sp,%bp # Packet pointer callw read # Read from disk + jc nread.1 # If error, fail lea 0x10(%bp),%sp # Clear stack - jnc return # If success, return - mov $msg_read,%si # Otherwise, set the error - # message and fall through to - # the error routine + mov $msg_dot,%si + call putstr + ret # If success, return +nread.1: mov %ah,%al # Format + mov $read_err,%di # error + call hex8 # code /* + movl 0x8(%bp),%eax # Format + mov $lba,%di # LBA + call hex32 + mov $msg_lba,%si # Display + call putstr # LBA + */ + mov $msg_read,%si # Set the error message and + # fall through to the error + # routine +/* * Print out the error message pointed to by %ds:(%si) followed * by a prompt, wait for a keypress, and then reboot the machine. */ @@ -259,14 +257,6 @@ putstr: lodsb # Get char jne putstr.0 # No /* - * Overused return code. ereturn is used to return an error from the - * read function. Since we assume putstr succeeds, we (ab)use the - * same code when we return from putstr. - */ -ereturn: movb $0x1,%ah # Invalid - stc # argument -return: retw # To caller -/* * Reads sectors from the disk. If EDD is enabled, then check if it is * installed and use it if it is. If it is not installed or not enabled, then * fall back to using CHS. Since we use a LBA, if we are using CHS, we have to @@ -294,14 +284,43 @@ read: cmpb $0x80,%dl # Hard drive? retw # To caller read.1: mov $msg_chs,%si jmp error -msg_chs: .asciz "CHS not supported" +/* + * Convert EAX, AX, or AL to hex, saving the result to [EDI]. + */ +/* +hex32: pushl %eax # Save + shrl $0x10,%eax # Do upper + call hex16 # 16 + popl %eax # Restore +hex16: call hex16.1 # Do upper 8 +hex16.1: xchgb %ah,%al # Save/restore + */ +hex8: push %ax # Save + shrb $0x4,%al # Do upper + call hex8.1 # 4 + pop %ax # Restore +hex8.1: andb $0xf,%al # Get lower 4 + cmpb $0xa,%al # Convert + sbbb $0x69,%al # to hex + das # digit + orb $0x20,%al # To lower case + stosb # Save char + ret # (Recursive) + /* Messages */ -msg_read: .asciz "Read" -msg_part: .asciz "Boot" +msg_chs: .asciz "CHS not supported" +msg_read: .ascii "Read error: " +read_err: .asciz "XX" +/* +msg_lba: .ascii "LBA: " +lba: .asciz "XXXXXXXX\r\n" + */ +msg_dot: .asciz "." +msg_part: .asciz "Boot error" -prompt: .asciz " error\r\n" +prompt: .asciz "\r\n" .org PRT_OFF,0x90 -- John Baldwin
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