The bulk of the iPXE binary (the .textdata section) is physically
relocated at runtime to the top of the 32-bit address space in order
to allow space for an OS to be loaded. The relocation is achieved
with the assistance of segmentation: we adjust the code and data
segment bases so that the link-time addresses remain valid.
Segmentation is not available (for normal code and data segments) in
long mode. We choose to compile the C code with -mcmodel=kernel and
use a link-time address of 0xffffffffeb000000. This choice allows us
to identity-map the entirety of the 32-bit address space, and to alias
our chosen link-time address to the physical location of our .textdata
section. (This requires the .textdata section to always be aligned to
a page boundary.)
We simultaneously choose to set the 32-bit virtual address segment
bases such that the link-time addresses may simply be truncated to 32
bits in order to generate a valid 32-bit virtual address. This allows
symbols in .textdata to be trivially accessed by both 32-bit and
64-bit code.
There is no (sensible) way in 32-bit assembly code to generate the
required R_X86_64_32S relocation records for these truncated symbols.
However, subtracting the fixed constant 0xffffffff00000000 has the
same effect as truncation, and can be represented in a standard
R_X86_64_32 relocation record. We define the VIRTUAL() macro to
abstract away this truncation operation, and apply it to all
references by 32-bit (or 16-bit) assembly code to any symbols within
the .textdata section.
We define "virt_offset" for a 64-bit build as "the value to be added
to an address within .textdata in order to obtain its physical
address". With this definition, the low 32 bits of "virt_offset" can
be treated by 32-bit code as functionally equivalent to "virt_offset"
in a 32-bit build.
We define "text16" and "data16" for a 64-bit build as the physical
addresses of the .text16 and .data16 sections. Since a physical
address within the 32-bit address space may be used directly as a
64-bit virtual address (thanks to the identity map), this definition
provides the most natural access to variables in .text16 and .data16.
Note that this requires a minor adjustment in prot_to_real(), which
accesses .text16 using 32-bit virtual addresses.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[librm] Transition to protected mode within init_librm()
Long-mode operation will require page tables, which are too large to
sensibly fit in our .data16 segment in base memory.
Add a portion of init_librm() running in 32-bit protected mode to
provide access to high memory. Use this portion of init_librm() to
initialise the .textdata variables "virt_offset", "text16", and
"data16", eliminating the redundant (re)initialisation currently
performed on every mode transition as part of real_to_prot().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Use the standard "pushl $function ; pushw %cs ; call prot_call"
sequence everywhere that prot_call() is used.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[bios] Make uses of REAL_CODE() and PHYS_CODE() 64-bit clean
On a 64-bit CPU, any modification of a register by 32-bit or 16-bit
code will destroy the invisible upper 32 bits of the corresponding
64-bit register. For example: a 32-bit "pushl %eax" followed by a
"popl %eax" will zero the upper half of %rax. This differs from the
treatment of upper halves of 32-bit registers by 16-bit code: a
"pushw %ax" followed by a "popw %ax" will leave the upper 16 bits of
%eax unmodified.
Inline assembly generated using REAL_CODE() or PHYS_CODE() will
therefore have to preserve the upper halves of all registers, to avoid
clobbering registers that gcc expects to be preserved.
Output operands from REAL_CODE() and PHYS_CODE() assembly may
therefore contain undefined values in the upper 32 bits.
Fix by using explicit variable widths (e.g. uint32_t) for
non-discarded output operands, to ensure that undefined values in the
upper 32 bits of 64-bit registers are ignored.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Move most arch/i386 files to arch/x86, and adjust the contents of the
Makefiles and the include/bits/*.h headers to reflect the new
locations.
This patch makes no substantive code changes, as can be seen using a
rename-aware diff (e.g. "git show -M5").
This patch does not make the pcbios platform functional for x86_64; it
merely allows it to compile without errors.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[prefix] Pad .text16 and .data16 segment sizes at build time
Commit c64747d ("[librm] Speed up real-to-protected mode transition
under KVM") rounded down the .text16 segment address calculated in
alloc_basemem() to a multiple of 64 bytes in order to speed up mode
transitions under KVM.
This creates a potential discrepancy between alloc_basemem() and
free_basemem(), meaning that free_basemem() may free less memory than
was allocated by alloc_basemem().
Fix by padding the calculated sizes of both .text16 and .data16 to a
multiple of 64 bytes at build time.
Debugged-by: Yossef Efraim <yossefe@mellanox.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Provide a debug function check_bios_interrupts() to look for changes
to the interrupt vector table. This can be useful when investigating
the behaviour (including crashes) of external PXE NBPs.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[romprefix] Report an optimistic runtime size estimate
Commit 5de45cd ("[romprefix] Report a pessimistic runtime size
estimate") set the PCI3.0 "runtime size" field equal to the worst-case
runtime size, on the basis that there is no guarantee that PMM
allocation will succeed and hence no guarantee that we will be able to
shrink the ROM image.
On a PCI3.0 system where PMM allocation would succeed, this can cause
the BIOS to unnecessarily refuse to initialise the iPXE ROM due to a
perceived shortage of option ROM space.
Fix by reporting the best-case runtime size via the PCI header, and
checking that we have sufficient runtime space (if applicable). This
allows iPXE ROMs to initialise on PCI3.0 systems that might otherwise
fail due to a shortage of option ROM space.
This may cause iPXE ROMs to fail to initialise on PCI3.0 systems where
PMM is broken. (Pre-PCI3.0 systems are unaffected since there must
already have been sufficient option ROM space available for the
initialisation entry point to be called.)
On balance, it seems preferable to avoid breaking "good" systems
(PCI3.0 with working PMM) at the cost of potentially breaking "bad"
systems (PCI3.0 with broken PMM).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[vmware] Expose GuestRPC mechanism in 64-bit builds
The GuestRPC mechanism (used for VMWARE_SETTINGS and CONSOLE_VMWARE)
does not use any real-mode code and so can be exposed in both 64-bit
and 32-bit builds.
Reported-by: Matthew Helton <mwhelton@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
When USB network card drivers are used, the BIOS' legacy USB
capability is necessarily disabled since there is no way to share the
host controller between the BIOS and iPXE.
Commit 3726722 ("[usb] Add basic support for USB keyboards") added
support allowing a USB keyboard to be used within iPXE. However,
external code such as a PXE NBP has no way to utilise this support,
and so a USB keyboard cannot be used to control a PXE NBP loaded from
a USB network card.
Add support for injecting keypresses from any iPXE console into the
BIOS keyboard buffer. This allows external code such as a PXE NBP to
function with a USB keyboard even after the BIOS' legacy USB
capability has been disabled.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[comboot] Reset console before starting COMBOOT executable
iPXE does not call shutdown() before invoking a COMBOOT executable,
since the executable is allowed to make API calls back into iPXE. If
a background picture is used, then the console will not be restored to
text mode before invoking the COMBOOT executable. This can cause
undefined behaviour.
Fix by adding an explicit call to console_reset() immediately before
invoking a COMBOOT or COM32 executable, analogous to the call made to
console_reset() immediately before invokving a PXE NBP.
Debugged-by: Andrew Widdersheim <awiddersheim@inetu.net>
Tested-by: Andrew Widdersheim <awiddersheim@inetu.net>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[build] Generalise CONSOLE_VESAFB to CONSOLE_FRAMEBUFFER
The name "vesafb" is intrinsically specific to a BIOS environment.
Generalise the build configuration option CONSOLE_VESAFB to
CONSOLE_FRAMEBUFFER, in preparation for adding EFI framebuffer
support.
Existing configurations using CONSOLE_VESAFB will continue to work.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[pxe] Notify BIOS via INT 1a,564e for each new network device
Use INT 1a,564e to notify the BIOS of each network device that we
detect. This provides an opportunity for the BIOS to implement
platform policy such as changing the MAC address by issuing a call to
PXENV_UNDI_SET_STATION_ADDRESS.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[pxe] Invoke INT 1a,564e when PXE stack is activated
Invoke INT 1a,564e whenever a PXE stack is activated, passing the
address of the PXENV+ structure in %es:%bx. This is designed to allow
a BIOS to be notified when a PXE stack has been installed, providing
an opportunity for start-of-day commands such as setting the MAC
address according to a policy chosen by the BIOS.
PXE defines INT 1a,5650 as a means of locating the PXENV+ structure:
this call returns %ax=0x564e and the address of the PXENV+ structure
in %es:%bx. We choose INT 1a,564e as a fairly natural notification
call, using the parameters as would be returned by INT 1a,5650.
The full calling convention (documented as per section 3.1 of the PXE
specification) is:
INT 1a,564e - PXE installation notification
Enter:
%ax = 0x564e
%es = 16-bit segment address of the PXENV+ structure
%bx = 16-bit offset of the PXENV+ structure
Exit:
%edx may be trashed (as is the case for INT 1a,5650)
All other register contents must be preserved
CF is cleared
IF is preserved
All other flags are undefined
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Merge the functionality of parse_next_server_and_filename() and
tftp_uri() into a single pxe_uri(), which takes a server address
(IPv4/IPv6/none) and a filename, and produces a URI using the rule:
- if the filename is a hierarchical absolute URI (i.e. includes a
scheme such as "http://" or "tftp://") then use that URI and ignore
the server address,
- otherwise, if the server address is recognised (according to
sa_family) then construct a TFTP URI based on the server address,
port, and filename
- otherwise fail.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[build] Search for ldlinux.c32 separately from isolinux.bin
Some distributions (observed with Ubuntu 15.04) place ldlinux.c32 in a
separate directory from isolinux.bin. Search for these files
separately, and allow an alternative location of ldlinux.c32 to be
provided via LDLINUX_C32=... on the make command line.
Reported-by: Adrian Koshka <adriankoshcha@teknik.io>
Tested-by: Adrian Koshka <adriankoshcha@teknik.io>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[pxe] Construct all fake DHCP packets before starting PXE NBP
Commit edf74df ("[pxe] Always reconstruct packet for
PXENV_GET_CACHED_INFO") fixed the problems caused by returning stale
DHCP packets (e.g. from an earlier boot attempt using a different
network device), but broke interoperability with NBPs such as WDS
which may overwrite our cached (fake) DHCP packets and expect the
modified packets to be returned by a subsequent call to
PXENV_GET_CACHED_INFO.
Fix by constructing the fake DHCP packets immediately before
transferring control to a PXE NBP. Calls to PXENV_GET_CACHED_INFO
will now never modify the cached packets.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[pxe] Warn about PXE NBPs that may be EFI executables
A relatively common user mistake is to attempt to boot an EFI
executable (such as grub.efi) using a BIOS version of iPXE.
Unfortunately there are no signature checks that we can use to
unambiguously identify a PXE NBP, since a PXE NBP is just raw machine
code. We therefore have to accept anything sufficiently small to fit
into base memory as a valid PXE NBP.
We can detect that a file might be an EFI executable by checking for
the initial "MZ" signature bytes. This does not necessarily preclude
the file from also being a PXE NBP (since it would be possible to
create a hybrid binary which acts as both an EFI executable and a PXE
NBP, similar to the way in which wimboot and the Linux kernel are
hybrid binaries which act as both an EFI executable and a bzImage).
If the initial "MZ" signature bytes are present, then attempt to warn
the user by setting the image type to "PXE-NBP (may be EFI?)". We
can't (sensibly) prevent the user from accidentally running an EFI
executable as a PXE NBP, but we can at least make it easier for the
user to identify their mistake.
Inspired-by: Robin Smidsrød <robin@smidsrod.no>
Inspired-by: Wissam Shoukair <wissams@mellanox.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
UEFI platforms may provide a watchdog timer, which will reboot the
machine if an operating system takes more than five minutes to load.
This can cause long-lived iPXE downloads (or interactive shell
sessions) to unexpectedly reboot.
Fix by resetting the watchdog timer every ten seconds while the iPXE
main processing loop continues to run.
Reported-by: Bradley B Williams <bradleybwilliams@swbell.net>
Reported-by: John Clark <john.r.clark.3@gmail.com>
Reported-by: wdriever@gmail.com
Reported-by: Charlie Beima <cbeima@indiana.edu>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[serial] Check for UART existence in uart_select()
Check for existence of the UART in uart_select(), not just in
uart_init(). This allows uart_select() to refuse to set a non-working
address in uart->base, which in turns means that the serial console
code will not attempt to use a non-existent UART.
Reported-by: Torgeir Wulfsberg <Torgeir.Wulfsberg@kongsberg.com>
Reported-by: Ján ONDREJ (SAL) <ondrejj@salstar.sk>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[comboot] Avoid dragging in serial console support unconditionally
When the ability for iPXE to handle multiple serial ports was added,
the choice was made that the singular serial port referred to by
COMBOOT calls should mean the port used for the serial console. This
unintentionally caused IMAGE_COMBOOT to also enable CONSOLE_SERIAL.
Fix by providing a weak-symbol version of the serial console which
will be used if serial console support was not explicitly enabled.
Reported-by: Torgeir Wulfsberg <Torgeir.Wulfsberg@kongsberg.com>
Reported-by: Ján ONDREJ (SAL) <ondrejj@salstar.sk>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
We do not set up any kind of virtual addressing before invoking an
ELFBoot image. Reject if the image's program headers indicate that
virtual addresses are not equal to physical addresses.
This avoids problems when loading some RHEL5 kernels, which seem to
include ELFBoot headers using virtual addressing. With this change,
these kernels are no longer detected as ELFBoot, and so may be
(correctly) detected as bzImage instead.
Reported-by: Torgeir.Wulfsberg@kongsberg.com
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown