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authorru <ru@FreeBSD.org>2004-04-28 14:31:44 +0000
committerru <ru@FreeBSD.org>2004-04-28 14:31:44 +0000
commit7094a911cb0108eb988c5f9f2bbac09e0a4bdc22 (patch)
tree6526cb230b92f6b3ba8cc2d4a497135c33f78806 /sys/boot/i386/pxeldr
parent2f1180c1cac0aad3a7c2b71fd3c73b0c81f46cd6 (diff)
downloadFreeBSD-src-7094a911cb0108eb988c5f9f2bbac09e0a4bdc22.zip
FreeBSD-src-7094a911cb0108eb988c5f9f2bbac09e0a4bdc22.tar.gz
After talking to Bruce Evans and reading more standards specs,
switch to using C99-style comments everywhere in preprocessed assembler. The reason is that lines starting with the regexp '^[[:space:]]#' are treated as preprocessing directives, and while it seems to work now with GCC, it's not necessarily has to work. Use C99 comments `//' for the trailing comments to save whitespace.
Diffstat (limited to 'sys/boot/i386/pxeldr')
-rw-r--r--sys/boot/i386/pxeldr/pxeldr.S330
1 files changed, 167 insertions, 163 deletions
diff --git a/sys/boot/i386/pxeldr/pxeldr.S b/sys/boot/i386/pxeldr/pxeldr.S
index 25ab5c0..7c09c8a 100644
--- a/sys/boot/i386/pxeldr/pxeldr.S
+++ b/sys/boot/i386/pxeldr/pxeldr.S
@@ -19,7 +19,7 @@
* This simple program is a preloader for the normal boot3 loader. It is simply
* prepended to the beginning of a fully built and btxld'd loader. It then
* copies the loader to the address boot2 normally loads it, emulates the
- * boot[12] environment (protected mode, a bootinfo struct, etc.), and then jumps
+ * boot[12] environment (protected mode, a bootinfo struct, etc.) and then jumps
* to the start of btxldr to start the boot process. This method allows a stock
* /boot/loader to be booted over the network via PXE w/o having to write a
* separate PXE-aware client just to load the loader.
@@ -28,45 +28,45 @@
/*
* Memory locations.
*/
- .set MEM_PAGE_SIZE,0x1000 # memory page size, 4k
- .set MEM_ARG,0x900 # Arguments at start
- .set MEM_ARG_BTX,0xa100 # Where we move them to so the
- # BTX client can see them
- .set MEM_ARG_SIZE,0x18 # Size of the arguments
- .set MEM_BTX_ADDRESS,0x9000 # where BTX lives
- .set MEM_BTX_ENTRY,0x9010 # where BTX starts to execute
- .set MEM_BTX_OFFSET,MEM_PAGE_SIZE # offset of BTX in the loader
- .set MEM_BTX_CLIENT,0xa000 # where BTX clients live
- .set MEM_BIOS_KEYBOARD,0x496 # BDA byte with keyboard bit
+ .set MEM_PAGE_SIZE,0x1000 // memory page size, 4k
+ .set MEM_ARG,0x900 // Arguments at start
+ .set MEM_ARG_BTX,0xa100 // Where we move them to so the
+ // BTX client can see them
+ .set MEM_ARG_SIZE,0x18 // Size of the arguments
+ .set MEM_BTX_ADDRESS,0x9000 // where BTX lives
+ .set MEM_BTX_ENTRY,0x9010 // where BTX starts to execute
+ .set MEM_BTX_OFFSET,MEM_PAGE_SIZE // offset of BTX in the loader
+ .set MEM_BTX_CLIENT,0xa000 // where BTX clients live
+ .set MEM_BIOS_KEYBOARD,0x496 // BDA byte with keyboard bit
/*
* a.out header fields
*/
- .set AOUT_TEXT,0x04 # text segment size
- .set AOUT_DATA,0x08 # data segment size
- .set AOUT_BSS,0x0c # zero'd BSS size
- .set AOUT_SYMBOLS,0x10 # symbol table
- .set AOUT_ENTRY,0x14 # entry point
- .set AOUT_HEADER,MEM_PAGE_SIZE # size of the a.out header
+ .set AOUT_TEXT,0x04 // text segment size
+ .set AOUT_DATA,0x08 // data segment size
+ .set AOUT_BSS,0x0c // zero'd BSS size
+ .set AOUT_SYMBOLS,0x10 // symbol table
+ .set AOUT_ENTRY,0x14 // entry point
+ .set AOUT_HEADER,MEM_PAGE_SIZE // size of the a.out header
/*
* Flags for kargs->bootflags
*/
- .set KARGS_FLAGS_PXE,0x2 # flag to indicate booting from
- # PXE loader
+ .set KARGS_FLAGS_PXE,0x2 // flag to indicate booting from
+ // PXE loader
/*
* Boot howto bits
*/
- .set RB_SERIAL,0x1000 # serial console
+ .set RB_SERIAL,0x1000 // serial console
/*
* Segment selectors.
*/
- .set SEL_SDATA,0x8 # Supervisor data
- .set SEL_RDATA,0x10 # Real mode data
- .set SEL_SCODE,0x18 # PM-32 code
- .set SEL_SCODE16,0x20 # PM-16 code
+ .set SEL_SDATA,0x8 // Supervisor data
+ .set SEL_RDATA,0x10 // Real mode data
+ .set SEL_SCODE,0x18 // PM-32 code
+ .set SEL_SCODE16,0x20 // PM-16 code
/*
* BTX constants
*/
- .set INT_SYS,0x30 # BTX syscall interrupt
+ .set INT_SYS,0x30 // BTX syscall interrupt
/*
* Bit in MEM_BIOS_KEYBOARD that is set if an enhanced keyboard is present
*/
@@ -81,186 +81,190 @@
/*
* BTX program loader for PXE network booting
*/
-start: cld # string ops inc
- xorw %ax, %ax # zero %ax
- movw %ax, %ss # setup the
- movw $start, %sp # stack
- movw %es, %cx # save PXENV+ segment
- movw %ax, %ds # setup the
- movw %ax, %es # data segments
- andl $0xffff, %ecx # clear upper words
- andl $0xffff, %ebx # of %ebx and %ecx
- shll $4, %ecx # calculate the offset of
- addl %ebx, %ecx # the PXENV+ struct and
- pushl %ecx # save it on the stack
- movw $welcome_msg, %si # %ds:(%si) -> welcome message
- callw putstr # display the welcome message
+start: cld // string ops inc
+ xorw %ax, %ax // zero %ax
+ movw %ax, %ss // setup the
+ movw $start, %sp // stack
+ movw %es, %cx // save PXENV+ segment
+ movw %ax, %ds // setup the
+ movw %ax, %es // data segments
+ andl $0xffff, %ecx // clear upper words
+ andl $0xffff, %ebx // of %ebx and %ecx
+ shll $4, %ecx // calculate the offset of
+ addl %ebx, %ecx // the PXENV+ struct and
+ pushl %ecx // save it on the stack
+ movw $welcome_msg, %si // %ds:(%si) -> welcome message
+ callw putstr // display the welcome message
/*
* Setup the arguments that the loader is expecting from boot[12]
*/
- movw $bootinfo_msg, %si # %ds:(%si) -> boot args message
- callw putstr # display the message
- movw $MEM_ARG, %bx # %ds:(%bx) -> boot args
- movw %bx, %di # %es:(%di) -> boot args
- xorl %eax, %eax # zero %eax
- movw $(MEM_ARG_SIZE/4), %cx # Size of arguments in 32-bit
- # dwords
- rep # Clear the arguments
- stosl # to zero
- orb $KARGS_FLAGS_PXE, 0x8(%bx) # kargs->bootflags |=
- # KARGS_FLAGS_PXE
- popl 0xc(%bx) # kargs->pxeinfo = *PXENV+
+ movw $bootinfo_msg, %si // %ds:(%si) -> boot args
+ // message
+ callw putstr // display the message
+ movw $MEM_ARG, %bx // %ds:(%bx) -> boot args
+ movw %bx, %di // %es:(%di) -> boot args
+ xorl %eax, %eax // zero %eax
+ movw $(MEM_ARG_SIZE/4), %cx // Size of arguments in 32-bit
+ // dwords
+ rep // Clear the arguments
+ stosl // to zero
+ orb $KARGS_FLAGS_PXE, 0x8(%bx) // kargs->bootflags |=
+ // KARGS_FLAGS_PXE
+ popl 0xc(%bx) // kargs->pxeinfo = *PXENV+
#ifdef ALWAYS_SERIAL
/*
* set the RBX_SERIAL bit in the howto byte.
*/
- orl $RB_SERIAL, (%bx) # enable serial console
+ orl $RB_SERIAL, (%bx) // enable serial console
#endif
#ifdef PROBE_KEYBOARD
/*
* Look at the BIOS data area to see if we have an enhanced keyboard. If not,
* set the RBX_SERIAL bit in the howto byte.
*/
- testb $KEYBOARD_BIT, MEM_BIOS_KEYBOARD # keyboard present?
- jnz keyb # yes, so skip
- orl $RB_SERIAL, (%bx) # enable serial console
+ testb $KEYBOARD_BIT, MEM_BIOS_KEYBOARD // keyboard present?
+ jnz keyb // yes, so skip
+ orl $RB_SERIAL, (%bx) // enable serial console
keyb:
#endif
/*
* Turn on the A20 address line
*/
- callw seta20 # Turn A20 on
+ callw seta20 // Turn A20 on
/*
* Relocate the loader and BTX using a very lazy protected mode
*/
- movw $relocate_msg, %si # Display the
- callw putstr # relocation message
- movl end+AOUT_ENTRY, %edi # %edi is the destination
- movl $(end+AOUT_HEADER), %esi # %esi is
- # the start of the text
- # segment
- movl end+AOUT_TEXT, %ecx # %ecx = length of the text
- # segment
- lgdt gdtdesc # setup our own gdt
- cli # turn off interrupts
- movl %cr0, %eax # Turn on
- orb $0x1, %al # protected
- movl %eax, %cr0 # mode
- ljmp $SEL_SCODE,$pm_start # long jump to clear the
- # instruction pre-fetch queue
+ movw $relocate_msg, %si // Display the
+ callw putstr // relocation message
+ movl end+AOUT_ENTRY, %edi // %edi is the destination
+ movl $(end+AOUT_HEADER), %esi // %esi is
+ // the start of the text
+ // segment
+ movl end+AOUT_TEXT, %ecx // %ecx = length of the text
+ // segment
+ lgdt gdtdesc // setup our own gdt
+ cli // turn off interrupts
+ movl %cr0, %eax // Turn on
+ orb $0x1, %al // protected
+ movl %eax, %cr0 // mode
+ ljmp $SEL_SCODE,$pm_start // long jump to clear the
+ // instruction pre-fetch queue
.code32
-pm_start: movw $SEL_SDATA, %ax # Initialize
- movw %ax, %ds # %ds and
- movw %ax, %es # %es to a flat selector
- rep # Relocate the
- movsb # text segment
- addl $(MEM_PAGE_SIZE - 1), %edi # pad %edi out to a new page
- andl $~(MEM_PAGE_SIZE - 1), %edi # for the data segment
- movl end+AOUT_DATA, %ecx # size of the data segment
- rep # Relocate the
- movsb # data segment
- movl end+AOUT_BSS, %ecx # size of the bss
- xorl %eax, %eax # zero %eax
- addb $3, %cl # round %ecx up to
- shrl $2, %ecx # a multiple of 4
- rep # zero the
- stosl # bss
- movl end+AOUT_ENTRY, %esi # %esi -> relocated loader
- addl $MEM_BTX_OFFSET, %esi # %esi -> BTX in the loader
- movl $MEM_BTX_ADDRESS, %edi # %edi -> where BTX needs to go
- movzwl 0xa(%esi), %ecx # %ecx -> length of BTX
- rep # Relocate
- movsb # BTX
- ljmp $SEL_SCODE16,$pm_16 # Jump to 16-bit PM
+pm_start: movw $SEL_SDATA, %ax // Initialize
+ movw %ax, %ds // %ds and
+ movw %ax, %es // %es to a flat selector
+ rep // Relocate the
+ movsb // text segment
+ addl $(MEM_PAGE_SIZE - 1), %edi // pad %edi out to a new page
+ andl $~(MEM_PAGE_SIZE - 1), %edi // for the data segment
+ movl end+AOUT_DATA, %ecx // size of the data segment
+ rep // Relocate the
+ movsb // data segment
+ movl end+AOUT_BSS, %ecx // size of the bss
+ xorl %eax, %eax // zero %eax
+ addb $3, %cl // round %ecx up to
+ shrl $2, %ecx // a multiple of 4
+ rep // zero the
+ stosl // bss
+ movl end+AOUT_ENTRY, %esi // %esi -> relocated loader
+ addl $MEM_BTX_OFFSET, %esi // %esi -> BTX in the loader
+ movl $MEM_BTX_ADDRESS, %edi // %edi -> where BTX needs to go
+ movzwl 0xa(%esi), %ecx // %ecx -> length of BTX
+ rep // Relocate
+ movsb // BTX
+ ljmp $SEL_SCODE16,$pm_16 // Jump to 16-bit PM
.code16
-pm_16: movw $SEL_RDATA, %ax # Initialize
- movw %ax, %ds # %ds and
- movw %ax, %es # %es to a real mode selector
- movl %cr0, %eax # Turn off
- andb $~0x1, %al # protected
- movl %eax, %cr0 # mode
- ljmp $0,$pm_end # Long jump to clear the
- # instruction pre-fetch queue
-pm_end: sti # Turn interrupts back on now
+pm_16: movw $SEL_RDATA, %ax // Initialize
+ movw %ax, %ds // %ds and
+ movw %ax, %es // %es to a real mode selector
+ movl %cr0, %eax // Turn off
+ andb $~0x1, %al // protected
+ movl %eax, %cr0 // mode
+ ljmp $0,$pm_end // Long jump to clear the
+ // instruction pre-fetch queue
+pm_end: sti // Turn interrupts back on now
/*
* Copy the BTX client to MEM_BTX_CLIENT
*/
- xorw %ax, %ax # zero %ax and set
- movw %ax, %ds # %ds and %es
- movw %ax, %es # to segment 0
- movw $MEM_BTX_CLIENT, %di # Prepare to relocate
- movw $btx_client, %si # the simple btx client
- movw $(btx_client_end-btx_client), %cx # length of btx client
- rep # Relocate the
- movsb # simple BTX client
+ xorw %ax, %ax // zero %ax and set
+ movw %ax, %ds // %ds and %es
+ movw %ax, %es // to segment 0
+ movw $MEM_BTX_CLIENT, %di // Prepare to relocate
+ movw $btx_client, %si // the simple btx client
+ movw $(btx_client_end-btx_client), %cx // length of btx client
+ rep // Relocate the
+ movsb // simple BTX client
/*
* Copy the boot[12] args to where the BTX client can see them
*/
- movw $MEM_ARG, %si # where the args are at now
- movw $MEM_ARG_BTX, %di # where the args are moving to
- movw $(MEM_ARG_SIZE/4), %cx # size of the arguments in longs
- rep # Relocate
- movsl # the words
+ movw $MEM_ARG, %si // where the args are at now
+ movw $MEM_ARG_BTX, %di // where the args are moving to
+ movw $(MEM_ARG_SIZE/4), %cx // size of the arguments in
+ // longs
+ rep // Relocate
+ movsl // the words
/*
* Save the entry point so the client can get to it later on
*/
- movl end+AOUT_ENTRY, %eax # load the entry point
- stosl # add it to the end of the
- # arguments
+ movl end+AOUT_ENTRY, %eax // load the entry point
+ stosl // add it to the end of the
+ // arguments
/*
* Now we just start up BTX and let it do the rest
*/
- movw $jump_message, %si # Display the
- callw putstr # jump message
- ljmp $0,$MEM_BTX_ENTRY # Jump to the BTX entry point
+ movw $jump_message, %si // Display the
+ callw putstr // jump message
+ ljmp $0,$MEM_BTX_ENTRY // Jump to the BTX entry point
/*
* Display a null-terminated string
*/
-putstr: lodsb # load %al from %ds:(%si)
- testb %al,%al # stop at null
- jnz putc # if the char != null, output it
- retw # return when null is hit
-putc: movw $0x7,%bx # attribute for output
- movb $0xe,%ah # BIOS: put_char
- int $0x10 # call BIOS, print char in %al
- jmp putstr # keep looping
+putstr: lodsb // load %al from %ds:(%si)
+ testb %al,%al // stop at null
+ jnz putc // if the char != null,
+ // output it
+ retw // return when null is hit
+putc: movw $0x7,%bx // attribute for output
+ movb $0xe,%ah // BIOS: put_char
+ int $0x10 // call BIOS, print char in %al
+ jmp putstr // keep looping
/*
* Enable A20
*/
-seta20: cli # Disable interrupts
-seta20.1: inb $0x64,%al # Get status
- testb $0x2,%al # Busy?
- jnz seta20.1 # Yes
- movb $0xd1,%al # Command: Write
- outb %al,$0x64 # output port
-seta20.2: inb $0x64,%al # Get status
- testb $0x2,%al # Busy?
- jnz seta20.2 # Yes
- movb $0xdf,%al # Enable
- outb %al,$0x60 # A20
- sti # Enable interrupts
- retw # To caller
+seta20: cli // Disable interrupts
+seta20.1: inb $0x64,%al // Get status
+ testb $0x2,%al // Busy?
+ jnz seta20.1 // Yes
+ movb $0xd1,%al // Command: Write
+ outb %al,$0x64 // output port
+seta20.2: inb $0x64,%al // Get status
+ testb $0x2,%al // Busy?
+ jnz seta20.2 // Yes
+ movb $0xdf,%al // Enable
+ outb %al,$0x60 // A20
+ sti // Enable interrupts
+ retw // To caller
/*
* BTX client to start btxldr
*/
.code32
btx_client: movl $(MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE-4), %esi
- # %ds:(%esi) -> end
- # of boot[12] args
- movl $(MEM_ARG_SIZE/4), %ecx # Number of words to push
- std # Go backwards
-push_arg: lodsl # Read argument
- pushl %eax # Push it onto the stack
- loop push_arg # Push all of the arguments
- cld # In case anyone depends on this
- pushl MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE # Entry point of
- # the loader
- pushl %eax # Emulate a near call
- movl $0x1, %eax # 'exec' system call
- int $INT_SYS # BTX system call
+ // %ds:(%esi) -> end
+ // of boot[12] args
+ movl $(MEM_ARG_SIZE/4), %ecx // Number of words to push
+ std // Go backwards
+push_arg: lodsl // Read argument
+ pushl %eax // Push it onto the stack
+ loop push_arg // Push all of the arguments
+ cld // In case anyone depends
+ // on this
+ pushl MEM_ARG_BTX-MEM_BTX_CLIENT+MEM_ARG_SIZE // Entry point of
+ // the loader
+ pushl %eax // Emulate a near call
+ movl $0x1, %eax // 'exec' system call
+ int $INT_SYS // BTX system call
btx_client_end:
.code16
@@ -268,17 +272,17 @@ btx_client_end:
/*
* Global descriptor table.
*/
-gdt: .word 0x0,0x0,0x0,0x0 # Null entry
- .word 0xffff,0x0,0x9200,0xcf # SEL_SDATA
- .word 0xffff,0x0,0x9200,0x0 # SEL_RDATA
- .word 0xffff,0x0,0x9a00,0xcf # SEL_SCODE (32-bit)
- .word 0xffff,0x0,0x9a00,0x8f # SEL_SCODE16 (16-bit)
+gdt: .word 0x0,0x0,0x0,0x0 // Null entry
+ .word 0xffff,0x0,0x9200,0xcf // SEL_SDATA
+ .word 0xffff,0x0,0x9200,0x0 // SEL_RDATA
+ .word 0xffff,0x0,0x9a00,0xcf // SEL_SCODE (32-bit)
+ .word 0xffff,0x0,0x9a00,0x8f // SEL_SCODE16 (16-bit)
gdt.1:
/*
* Pseudo-descriptors.
*/
-gdtdesc: .word gdt.1-gdt-1 # Limit
- .long gdt # Base
+gdtdesc: .word gdt.1-gdt-1 // Limit
+ .long gdt // Base
welcome_msg: .asciz "PXE Loader 1.00\r\n\n"
bootinfo_msg: .asciz "Building the boot loader arguments\r\n"
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