Add basic support for Xen PV-HVM domains (detected via the Xen
platform PCI device with IDs 5853:0001), including support for
accessing configuration via XenStore and enumerating devices via
XenBus.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
When a 32-bit iPXE binary is running on a system which allocates PCI
memory BARs above 4GB, our PCI subsystem will return the base address
for any such BARs as zero (with a warning message if DEBUG=pci is
enabled). Currently, ioremap() will happily map an address pointing
to the start of physical memory, providing no sensible indication of
failure.
Fix by always returning NULL if we are asked to ioremap() a zero bus
address.
With a totally flat memory model (e.g. under EFI), this provides an
accurate failure indication since no PCI peripheral will be mapped to
the zero bus address.
With the librm memory model, there is the possibility of a spurious
NULL return from ioremap() if the bus address happens to be equal to
virt_offset. Under the current virtual memory map, the NULL virtual
address will always be the start of .textdata, and so this problem
cannot occur; a NULL return from ioremap() will always be an accurate
failure indication.
Debugged-by: Anton D. Kachalov <mouse@yandex-team.ru>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Provide a single instance of EFI_DRIVER_BINDING_PROTOCOL (attached to
our image handle); this matches the expectations scattered throughout
the EFI specification.
Open the underlying hardware device using EFI_OPEN_PROTOCOL_BY_DRIVER
and EFI_OPEN_PROTOCOL_EXCLUSIVE, to prevent other drivers from
attaching to the same device.
Do not automatically connect to devices when being loaded as a driver;
leave this task to the platform firmware (or to the user, if loading
directly from the EFI shell).
When running as an application, forcibly disconnect any existing
drivers from devices that we want to control, and reconnect them on
exit.
Provide a meaningful driver version number (based on the build
timestamp), to allow platform firmware to automatically load newer
versions of iPXE drivers if multiple drivers are present.
Include device paths within debug messages where possible, to aid in
debugging.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some external code (observed with FreeBSD's bootloader) will continue
to make INT 13 calls after reconfiguring the 8259 PIC to change the
vector offsets for IRQs. If an IRQ (e.g. the timer IRQ) subsequently
occurs while iPXE is in protected mode, this will cause a general
protection fault since the corresponding IDT entry is empty.
A general protection fault is INT 0x0d, which happens to overlap with
the original IRQ5. We therefore do have an ISR set up to handle a
general protection fault, but this ISR simply reflects the interrupt
down to the real-mode INT 0x0d and then attempts to return. Since our
ISR is expecting a hardware interrupt rather than a general protection
fault, it doesn't remove the error code from the stack before issuing
the iret instruction; it therefore attempts to return to a garbage
address. Since the segment part of this address is likely to be
invalid, a second general protection fault occurs. This cycle
continues until we run out of stack space and triple fault.
Fix by reflecting all INTs down to real mode. This actually reduces
the code size by four bytes (but increases the bss size by almost
2kB).
Reported-by: Brian Rak <dn@devicenull.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The bzImage boot protocol allows the real-mode code to be loaded at
any segment within base memory. (The fact that both iPXE and recent
versions of Syslinux will load the real-mode code at 1000:0000 is a
coincidence; it is not guaranteed by the specification.)
Fix by making the code relocatable.
Reported-by: Andrew Stuart <andrew@shopcusa.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Rework geniso and genliso to provide a single merged utility for
generating ISO images.
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The .lkrn prefix currently provides a zImage kernel with unused setup
sectors and the whole iPXE binary placed within the "protected mode
kernel" portion of the zImage.
The work carried out years ago to create the .mrom format provides a
mechanism allowing the iPXE binary to be split into a small real-mode
header and a larger payload. This neatly matches the way that a
bzImage is loaded: the "setup sectors" can contain the header and the
"protected mode kernel" can contain the payload.
This removes the size restrictions on an iPXE .lkrn image (and hence
on derived image formats such as .iso).
Also remove obsolete copyright information, since none of the original
code or functionality now remains.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Interrupt processing adds noise to profiling results. Allow
interrupts (from within protected mode) to be profiled separately,
with time spent within the interrupt handler being excluded from any
other profiling currently in progress.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
PXENV_UNDI_ISR calls may implicitly refill the underlying receive
ring, and so could continue to retrieve packets indefinitely. Place
an upper limit on the number of calls to PXENV_UNDI_ISR per call to
undinet_poll().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
When making a call from real mode to protected mode, we save and
restore the global and interrupt descriptor table registers. The
restore currently takes place after returning to real mode, which
generates two EXCEPTION_NMIs and corresponding VM exits when running
under KVM on an Intel CPU.
Avoid the VM exits by restoring the descriptor table registers inside
prot_to_real, while still running in protected mode.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Ensure that all segment registers have zero in the low two bits before
transitioning to protected mode. This allows the CPU state to
immediately be deemed to be "valid", and eliminates the need for any
further emulated instructions.
Load the protected-mode interrupt descriptor table after switching to
protected mode, since this avoids triggering an EXCEPTION_NMI and
corresponding VM exit.
This reduces the time taken by real_to_prot under KVM by around 50%.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
On an Intel CPU supporting VMX, KVM will emulate instructions while
the CPU state remains "invalid". In real mode, the CPU state is
defined to be "invalid" if any segment register has a base which is
not equal to (sreg<<4) or a limit which is not equal to 64kB.
We don't actually use the base stored in the REAL_DS descriptor for
any significant purpose. Change the base stored in this descriptor to
be equal to (REAL_DS<<4). A segment register loaded with REAL_DS is
then automatically valid in both real and protected modes. This
allows KVM to stop emulating instructions much sooner.
The only use of REAL_DS for memory accesses currently occurs in the
indirect ljmp within prot_to_real. Change this to a direct ljmp,
storing rm_cs in .text16 as part of the ljmp instruction. This
removes the only memory access via REAL_DS (thereby allowing for the
above descriptor base address hack), and also simplifies the ljmp
instruction (which will still have to be emulated).
Load the real-mode interrupt descriptor table register before
switching to real mode, since this avoids triggering an EXCEPTION_NMI
and corresponding VM exit.
This reduces the time taken by prot_to_real under KVM by around 65%.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The mode-transition code involves paths which switch back and forth
between the .text and .text16 sections. At present, only the start of
each function is labelled, which makes it difficult to decode
addresses within the parts of the function existing in a different
section.
Add explicit labels at the start of each section change, so that
addresses can be meaningfully decoded to the nearest label.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Now that we can handle interrupts while in protected mode, there is no
need to switch to real mode just to halt the CPU.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The currticks() function is called at least once per TCP packet, and
so is performance-critical. Switching to real mode just to allow the
timer interrupt to fire is expensive when running inside a virtual
machine, and imposes a significant performance cost.
Fix by enabling interrupts without switching to real mode. This
results in an approximately 100% increase in download speed when
running under KVM.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
We now have the ability to handle interrupts while in protected mode,
and so no longer need to set up a dedicated interrupt descriptor table
while running COM32 executables.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
When running in a virtual machine, switching to real mode may be
expensive. Allow interrupts to be enabled while in protected mode and
reflected down to the real-mode interrupt handlers.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
We currently use flat real mode wherever real mode is required. This
guarantees that we will not surprise some unsuspecting external caller
which has carefully set up flat real mode by suddenly reducing the
segment limits to 64kB.
However, operating in flat real mode imposes a severe performance
penalty in some virtualisation environments, since some CPUs cannot
fully virtualise flat real mode and so the hypervisor must fall back
to emulation. In particular, operating under KVM on a pre-Westmere
Intel CPU will be at least an order of magnitude slower, to the point
that there is a visible teletype effect when printing anything to the
BIOS console. (Older versions of KVM used to cheat and ignore the
"flat" part of flat real mode, which masked the problem.)
Switch (back) to using genuine real mode with 64kB segment limits
instead of flat real mode. Hopefully this won't break anything.
Add an explicit switch to flat real mode before returning to the BIOS
from the ROM prefix, since we know that a PMM BIOS will call the ROM
initialisation point (and potentially the BEV) in flat real mode.
As noted in previous commit messages, it is not possible to restore
the real-mode segment limits after a transition to protected mode,
since there is no way to know which protected-mode segment descriptor
was originally used to initialise the limit portion of the segment
register.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
We observed some time ago (in commit 4ce8d61 "Import various libgcc
functions from syslinux") that gcc seems to treat calls to the
implicit arithmetic functions (e.g. __udivdi3()) as being affected by
-mregparm but unaffected by -mrtd.
This seems to be no longer the case with current gcc versions, which
treat calls to these functions as being affected by both -mregparm and
-mrtd, as expected.
There is nothing obvious in the gcc changelogs to indicate precisely
when this happened. From experimentation with available gcc versions,
the change occurred sometime between v4.6.3 and v4.7.2. We assume
that only versions up to v4.6.x require the special treatment.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some BIOSes (observed with a ProLiant DL360p Gen8 SE) perform no range
checking whatsoever on the parameters passed to INT10,06 and will
therefore happily write to an area beyond the end of video RAM. The
area immediately following the video RAM tends to be the VGA BIOS ROM
image. Overwriting the VGA BIOS leads to an interesting variety of
crashes and reboots.
Fix by specifying an exact width and height to be cleared, rather than
passing in large values and relying upon the BIOS to truncate them to
the appropriate range.
Reported-by: Alex Davies <adavies@jumptrading.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some UEFI builds will set up a timer to continuously poll any SNP
devices. This can drain packets from the network device's receive
queue before iPXE gets a chance to process them.
Use netdev_rx_[un]freeze() to explicitly indicate when we expect our
network devices to be driven via the external SNP API (as we do with
the UNDI API on the standard BIOS build), and disable the SNP API
except when receive queue processing is frozen.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
EFIRC() uses PLATFORM_TO_ERRNO(), which evaluates its argument twice
(and can't trivially use a braced-group expression or an inline
function to avoid this, since it gets used outside of function
context).
The expression "EFIRC(main())" will therefore end up calling main()
twice, which is not the intended behaviour. Every other instance of
EFIRC() is of the simple form "EFIRC(rc)", so fix by converting this
instance to match.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
iPXE will detect timeout failures in several situations: network
link-up, DHCP, TCP connection attempts, unacknowledged TCP data, etc.
This does not cover all possible circumstances. For example, if a
connection to a web server is successfully established and the web
server acknowledges the HTTP request but never sends any data in
response, then no timeout will be triggered. There is no timeout
defined within the HTTP specifications, and the underlying TCP
connection will not generate a timeout since it has no way to know
that the HTTP layer is expecting to receive data from the server.
Add a "--timeout" parameter to "imgfetch", "chain", etc. If no
progress is made (i.e. no data is downloaded) within the timeout
period, then the download will be aborted.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Commit c429bf0 ("[romprefix] Store boot bus:dev.fn address as autoboot
device location") introduced a regression by using register %cx to
temporarily hold the PCI bus:dev.fn address, despite the fact that %cx
was already being used to hold the stored BIOS stack segment.
Consequently, when returning to the BIOS after a failed or cancelled
boot attempt, iPXE would end up calling INT 18 with the stack segment
set equal to the PCI bus:dev.fn address. Writing to essentially
random areas of memory tends to upset even the more robust BIOSes.
Fix by using register %ax to temporarily hold the PCI bus:dev.fn
address.
Reported-by: Anton D. Kachalov <mouse@yandex-team.ru>
Tested-by: Anton D. Kachalov <mouse@yandex-team.ru>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
iPXE currently pads initrd images to a multiple of 4kB and inserts
zero padding between images, as required by some versions of the Linux
kernel. The overall length reported via the ramdisk_size field in the
bzImage header includes this zero padding.
This causes problems when using memdisk to load a gzip-compressed disk
image. memdisk treats the ramdisk_size field as containing the exact
length of the initrd image, and uses this length to locate the 8-byte
gzip footer. This will generally cause memdisk to fail to decompress
the disk image.
Fix by reporting the exact length of the initrd image set, including
any padding inserted between images but excluding any padding added at
the end of the final image.
Reported-by: Levente LEVAI <levail@aviatronic.hu>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
qemu can load an option ROM which is not associated with a particular
PCI device using the "-option-rom" syntax. Under these circumstances,
we should ignore the PCI bus:dev.fn address that we expect to find in
%ax on entry to the initialisation vector.
Fix by using the PCI bus:dev.fn address only if it is non-zero. Since
00:00.0 will always be the host bridge, it can never be the address of
a network card.
Reported-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown