Record the session ID (if any) provided by the server and attempt to
reuse it for any concurrent connections to the same server.
If multiple connections are initiated concurrently (e.g. when using
PeerDist) then defer sending the ClientHello for all but the first
connection, to allow time for the first connection to potentially
obtain a session ID (and thereby speed up the negotiation for all
remaining connections).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
On a Dell OptiPlex 7010, calling DisconnectController() on the LOM
device handle will lock up the system. Debugging shows that execution
is trapped in an infinite loop that is somehow trying to reconnect
drivers (without going via ConnectController()).
The problem can be reproduced in the UEFI shell with no iPXE code
present, by using the "disconnect" command. Experimentation shows
that the only fix is to unload (rather than just disconnect) the
"Ip4ConfigDxe" driver.
Add the concept of a blacklist of UEFI drivers that will be
automatically unloaded when iPXE runs as an application, and add the
Dell Ip4ConfigDxe driver to this blacklist.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The Option::ROM module recognizes and checks EFI header of image. The
disrom.pl utility dumps this header if is present.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The Option::ROM module now compares the Code Type in the PCIR header
to 0x00 (PC-AT) in order to check the presence of other header types
(PnP, UNDI, iPXE, etc). The validity of these headers are checked not
only by offset, but by range and signature checks also. The image
checksum and initial size also depends on Code Type.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
GCC 9 warns that abs() may truncate its signed long argument. Fix by
using labs() instead.
Reported-by: Martin Liška <mliska@suse.cz>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Fix strcmp() and strncmp() to return proper standard positive/negative
values for unequal strings. Current implementation is backwards
(i.e. the functions are returning negative when should be positive and
vice-versa).
Currently all consumers of these functions only check the return value
for ==0 or !=0 and so we can safely change the implementation without
breaking things.
Signed-off-by: Aaron Young <Aaron.Young@oracle.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Current (simplified):
1. InstallMultipleProtocolInterfaces
if err goto err_install_protocol_interface;
2. OpenProtocol(efi_nii_protocol_guid)
if err goto err_open_nii;
3. OpenProtocol(efi_nii31_protocol_guid)
if err goto err_open_nii31;
4. efi_child_add
if err goto err_efi_child_add;
...
err_efi_child_add:
CloseProtocol(efi_nii_protocol_guid) <= should be efi_nii31_protocol_guid
err_open_nii: <= should be err_open_nii31
CloseProtocol(efi_nii31_protocol_guid) <= should be efi_nii_protocol_guid
err_open_nii31: <= should be err_open_nii
UninstallMultipleProtocolInterfaces
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
PCI Configuration Space contains fields prog-if at the offset 0x09,
sub-class at the offset 0x0a and base-class at the offset 0x0b (it
respects little endian). PCIR structure uses these fields in the same
order.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Starting from binutils 2.31.0 (commit bd7ab16b) x86-64 assembler
generates R_X86_64_PLT32 instead of R_X86_64_PC32.
Acked-by: John Jolly <jjolly@suse.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The first adapters in this family are X2522-10, X2522-25, X2541 and
X2542.
These no longer use PCI BAR 0 for I/O, but use that for memory. In
other words, BAR 2 on SFN8xxx adapters now becomes BAR 0.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Devices that support jumbo frames will currently default to the
largest possible MTU. This assumption is valid for virtual adapters
such as virtio-net, where the MTU must have been configured by a
system administrator, but is unsafe in the general case of a physical
adapter.
Default to the standard Ethernet MTU, unless explicitly overridden
either by the driver or via the ${netX/mtu} setting.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Avoid calling rndis_halt() and rndis->op->close() twice if the call to
register_netdev() fails.
Reported-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some versions of gcc seem to silently accept an attempt to disable an
unrecognised warning (e.g. via -Wno-stringop-truncation) but will then
report the unrecognised warning if any other error occurs during the
build, resulting in a potentially misleading error message.
Avoid this potential confusion by using the positive-form tests in
order to determine the workaround CFLAGS.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The definition of version_response channel message in Linux doesn't
include version field, so the upcoming VMBus implementation in QEMU
doesn't set it either. Neither Windows nor Linux had any problem with
this.
The check against this field is redundant because the message is the
response to initiate_contact message containing the specific version
requested, so the response with version_supported=true is unambiguous.
Drop this check and don't rely on the field to be present in the
message.
Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
register_netdev expects ->hw_addr and ->ll_addr to be already filled,
so move it towards the end of register_rndis, after the respective
fields have been successfully queried from the underlying device.
Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The gcc 8 compiler introduces a warning for certain string
manipulation functions, flagging usages which _may_ not be intended.
An audit of the iPXE sources indicates all usages of strncat and
strncpy are as intended, so the warnings currently issued are not
helpful, especially if warnings are considered errors.
Fix by detecting gcc's support for -Wno-stringop-truncation and, if
detected, using that option to avoid the warning.
Signed-off-by: Bruce Rogers <brogers@suse.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Also-fixed-by: Christian Hesse <list@eworm.de>
Also-fixed-by: Roman Kagan <rkagan@virtuozzo.com>
Also-fixed-by: Bernhard M. Wiedemann <bwiedemann@suse.de>
Also-fixed-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
As pointedly documented in RFC7230 section 2.3, HTTP is a stateless
protocol: each request message can be understood in isolation from any
other requests or responses. Various authentication schemes such as
NTLM break this fundamental property of HTTP and rely on the same TCP
connection being reused.
Work around these broken authentication schemes by ensuring that the
most recently pooled connection is reused for the subsequent
authentication retry.
Reported-by: Andreas Hammarskjöld <junior@2PintSoftware.com>
Tested-by: Andreas Hammarskjöld <junior@2PintSoftware.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add the function mii_find() in order to locate the PHY address.
Signed-off-by: Sylvie Barlow <sylvie.c.barlow@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
We currently have no generic concept of a PHY address, since all
existing implementations simply hardcode the PHY address within the
MII access methods.
A bit-bashing MII interface will need to be provided with an explicit
PHY address in order to generate the correct waveform. Allow for this
by separating out the concept of a MII device (i.e. a specific PHY
address attached to a particular MII interface).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow the subsystem IDs to be used when checking for PXE stacks with
broken interrupt support.
Suggested-by: Levi Hsieh <Levi.Hsieh@dell.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The relocation type R_ARM_REL32 is generated when building
bin-arm32-efi/snp.efi using gcc 6.3 and ld 2.28.
R_ARM_REL32 is a program counter (PC) relative 32 bit relocation so we
can ignore it like all other PC relative relocations.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
When booting some versions of the UEFI shell, our driver binding
protocol's Supported() entry point is called at TPL_NOTIFY for no
discernible reason. Attempting to raise to TPL_CALLBACK triggers an
immediate assertion failure in the firmware.
Since our Supported() method can run at any TPL, fix by simply not
attempting to raise the TPL within this method.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Release SNP devices to allow the SAN booted image to use our
EFI_SIMPLE_NETWORK_PROTOCOL instance, and to ensure that the image is
started at TPL_APPLICATION.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The cipherstream xfer_window_changed() message is used to retrigger
the TLS transmit state machine. If the transmit state machine is
idle, then the window change message will not be propagated to the
plainstream interface. This can potentially cause the plainstream
interface peer (e.g. httpcore) to block waiting for a window change
message that will never arrive.
Fix by ensuring that the window change message is propagated to the
plainstream interface if the transmit state machine is idle. (If the
transmit state machine is not idle then the plainstream window will be
zero anyway.)
Signed-off-by: Michael Brown <mcb30@ipxe.org>
In TLS terminology a session conceptually spans multiple individual
connections, and essentially represents the stored cryptographic state
(master secret and cipher suite) required to establish communication
without going through the certificate and key exchange handshakes.
Rename tls_session to tls_connection in order to make the name
tls_session available to represent the session state.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
A failure in tls_generate_random() will result in a call to ref_put()
before the received data list has been initialised, which will cause
free_tls() to attempt to traverse an uninitialised list.
Fix by ensuring that all fields referenced by free_tls() are
initialised before any of the potential failure paths.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Commit 6149e0a ("[librm] Provide symbols for inline code placed into
other sections") may cause build failures due to duplicate label names
if the compiler chooses to duplicate inline assembly code.
Fix by using the "%=" special format string to include a
guaranteed-unique number within the label name.
The "%=" will be expanded only if constraints exist for the inline
assembly. This fix therefore requires that all REAL_CODE() fragments
use a (possibly empty) constraint list.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Provide symbols constructed from the object name and line number for
code fragments placed into alternative sections, such as inline
REAL_CODE() assembly placed into .text16. This simplifies the
debugging task of finding the source code corresponding to a given
instruction pointer.
Note that we cannot use __FUNCTION__ since it is not a preprocessor
macro and so cannot be concatenated with string literals.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
If the underlying PXE stack reports an invalid IRQ number (above
IRQ_MAX), treat this as equivalent to an empty IRQ number and fall
back to using polling mode.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The existence of MMX and SSE is required by the System V x86_64 ABI
and so is assumed by gcc, but these registers are not preserved by our
own interrupt handlers and are unlikely to be preserved by other
context switch handlers in a boot firmware environment.
Explicitly prevent gcc from using MMX or SSE registers to avoid
potential problems due to silent register corruption.
We must remove the %xmm0-%xmm5 clobbers from the x86_64 version of
hv_call() since otherwise gcc will complain about unknown register
names. Theoretically, we should probably add code to explicitly
preserve the %xmm0-%xmm5 registers across a hypercall, in order to
guarantee to external code that these registers remain unchanged. In
practice this is difficult since SSE registers are disabled by
default: for background information see commits 71560d1 ("[librm]
Preserve FPU, MMX and SSE state across calls to virt_call()") and
dd9a14d ("[librm] Conditionalize the workaround for the Tivoli VMM's
SSE garbling").
Signed-off-by: Michael Brown <mcb30@ipxe.org>
We currently perform various min-entropy calculations using build-time
floating-point arithmetic. No floating-point code ends up in the
final binary, since the results are eventually converted to integers
and asserted to be compile-time constants.
Though this mechanism is undoubtedly cute, it inhibits us from using
"-mno-sse" to prevent the use of SSE registers by the compiler.
Fix by using fixed-point arithmetic instead.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
This is required to work around a bug in some firmware versions.
Signed-off-by: Ameer Mahagneh <ameerm@mellanox.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow the ACPI power management timer to be used if enabled via
TIMER_ACPI in config/timer.h. This provides an alternative timer on
systems where the standard 8254 PIT is unavailable or unreliable.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some drivers are known to call the optional Map_Mem() callback without
first checking that the callback exists. Provide a usable basic
implementation of Map_Mem() along with the other callbacks that become
mandatory if Map_Mem() is provided.
Note that in theory the PCI I/O protocol is allowed to require
multiple calls to Map(), with each call handling only a subset of the
overall mapped range. However, the reference implementation in EDK2
assumes that a single Map() will always suffice, so we can probably
make the same simplifying assumption here.
Tested with the Intel E3522X2.EFI driver (which, incidentally, fails
to cleanly remove one of its mappings).
Originally-implemented-by: Maor Dickman <maord@mellanox.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The blocked link test in eth_slow_lacp_rx() is performed before the
actor TLV is copied to the partner TLV, and so must test the actor
state field rather than the partner state field.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some CAs provide non-functional OCSP servers, and some clients are
forced to operate on networks without access to the OCSP servers.
Allow the user to explicitly disable the use of OCSP checks by
undefining OCSP_CHECK in config/crypto.h.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Limit the profile sample count to INT_MAX to avoid both signed
overflow and a potential division by zero when updating the stored
mean value.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Mark the link as blocked if the LACP partner is not reporting itself
as being in sync, collecting, and distributing.
This matches the behaviour for STP: we mark the link as blocked if we
detect that the switch is actively blocking traffic, in order to
extend the DHCP discovery period and so prevent boot failures on
switches that take an excessively long time to enable ports.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Remove the global variable shomron_nodnic_supported, since it may have
different values for different PCI devices.
Originally-fixed-by: Mohammed Taha <mohammedt@mellanox.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
When DEBUG=librm_mgmt is enabled, intercept CPU exceptions and provide
a register and stack dump, then drop to an emergency shell. Exiting
from the shell will almost certainly not work, but this provides an
opportunity to view the register and stack dump and carry out some
basic debugging.
Note that we can intercept only the first 8 CPU exceptions, since a
PXE ROM is not permitted to rebase the PIC.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Commit c89a446 ("[efi] Run at TPL_CALLBACK to protect against UEFI
timers") introduced a regression in the EFI entropy gathering code.
When the EFI_RNG_PROTOCOL is not present, we fall back to using timer
interrupts (as for the BIOS build). Since timer interrupts are
disabled at TPL_CALLBACK, WaitForEvent() fails and no entropy can be
gathered.
Fix by dropping to TPL_APPLICATION while entropy gathering is enabled.
Reported-by: Andreas Hammarskjöld <junior@2PintSoftware.com>
Tested-by: Andreas Hammarskjöld <junior@2PintSoftware.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The iSCSI root path may contain a literal IPv6 address. Update the
parser to handle this address format correctly.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
As noted in the comments, UEFI manages to combines the all of the
worst aspects of both a polling design (inefficiency and inability to
sleep until something interesting happens) and of an interrupt-driven
design (the complexity of code that could be preempted at any time,
thanks to UEFI timers).
This causes problems in particular for UEFI USB keyboards: the
keyboard driver calls UsbAsyncInterruptTransfer() to set up a periodic
timer which is used to poll the USB bus. This poll may interrupt a
critical section within iPXE, typically resulting in list corruption
and either a hang or reboot.
Work around this problem by mirroring the BIOS design, in which we run
with interrupts disabled almost all of the time.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Reporting a completion via usb_complete() will pass control outside
the scope of xhci.c, and could potentially result in a further call to
xhci_event_poll() before returning from usb_complete(). Since we
currently update the event consumer counter only after calling
usb_complete(), this can result in duplicate completions and
consequent corruption of the submission TRB ring structures.
Fix by updating the event ring consumer counter before passing control
to usb_complete().
Reported-by: Andreas Hammarskjöld <junior@2PintSoftware.com>
Tested-by: Andreas Hammarskjöld <junior@2PintSoftware.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The i219 appears to have a seriously broken reset mechanism. After
any transmit or receive activity, resetting the card will break both
the transmit and receive datapaths until the next PCI bus reset.
The Linux and BSD drivers include a convoluted workaround authored by
Intel which involves setting a bit in the undocumented FEXTNVM11
register, then transmitting a dummy 512-byte packet containing garbage
data, then reconfiguring the receive descriptor prefetch thresholds
and temporarily reenabling the receive datapath. The comments in the
Intel fix do not even remotely match what the code actually does, and
the code accidentally leaves the transmitter enabled after use.
Experimentation suggests that an equivalent fix is to simply set the
undocumented bit in FEXTNVM11 before enabling the transmit or receive
descriptor rings.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Invalid protocol speed ID tables appear to be increasingly common in
the wild, to the point that it is infeasible to apply an explicit
XHCI_BAD_PSIV flag for each offending PCI device ID.
Fix by assuming an invalid PSI table as soon as any invalid value is
reported by the hardware.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some older versions of gcc (observed with gcc 4.7.2) report a spurious
uninitialised variable warning in ena_get_device_attributes(). Work
around this warning by manually inlining the relevant code (which has
only a single call site).
Reported-by: xbgmsharp <xbgmsharp@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The UNDI layer uses the NETDEV_IRQ_ENABLED flag to choose whether to
return PXENV_UNDI_ISR_OUT_OURS or PXENV_UNDI_ISR_OUT_NOT_OURS for a
given interrupt. For a network device that does not support
interrupts, the flag will never be set and so pxenv_undi_isr() will
always return PXENV_UNDI_ISR_OUT_NOT_OURS. This causes some NBPs
(such as lpxelinux.0) to hang.
Redefine NETDEV_IRQ_ENABLED as a simple administrative flag which can
be set even on network devices that do not support interrupts. This
allows pxenv_undi_isr() (which is the sole user of NETDEV_IRQ_ENABLED)
to function as expected by lpxelinux.0.
Signed-off-by: Martin Habets <mhabets@solarflare.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Most drivers do not utilise an MII interface, since the link state is
typically available directly from a memory-mapped register.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Using "ld --oformat binary" for mbr.bin and usbdisk.bin seems to cause
segmentation faults on some versions of binutils (observed on Fedora
27). Work around this problem by using ld to create an intermediate
ELF object, followed by objcopy (via the existing %.tmp -> %.bin rule)
to create the final binary.
Note that we cannot simply use a single-stage "objcopy -O binary"
since this will not process the relocation records for x86_64: see
commit 1afcccd ("[build] Do not use "objcopy -O binary" for objects
with relocation records").
Reported-by: Brent S <bts@square-r00t.net>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add missing FILE_LICENCE declarations to x86_64 headers based on the
corresponding i386 headers (from which the x86_64 headers were
originally derived).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The URIs printed as part of download progress messages are intended to
provide a quick visual progress indication to the user. Very long
query strings can render this visual indication useless in practice,
since the most important information (generally the URI host and path)
is drowned out by multiple lines of human-illegible URI-encoded data.
Omit the query string entirely from the download progress message.
For consistency and brevity, also omit the URI fragment along with the
username and password (which was previously redacted anyway).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The precise HTTP response status code is currently visible only at
DBGLVL_EXTRA. Allow for easier debugging by reporting the whole
status line at DBGLVL_LOG for any unsuccessful responses.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Xen 4.4 includes the device "device/suspend/event-channel" which does
not have a "backend" key. This currently causes the entire XenBus
device tree probe to fail.
Fix by skipping probe attempts for device types for which there is no
iPXE driver.
Debugged-by: Eytan Heidingsfeld <eytanh@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow individual authentication schemes to parse WWW-Authenticate
headers that do not comply with RFC2617.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Servers may provide multiple WWW-Authenticate headers, each offering a
different authentication scheme. We currently fail the request as
soon as we encounter an unrecognised scheme, which prevents subsequent
offers from succeeding.
Fix by silently ignoring headers for schemes that we do not recognise.
If no schemes are recognised then the request will eventually fail
anyway due to the 401 response code.
If multiple schemes are supported, arbitrarily choose the scheme
appearing first within the response headers.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Relocation type R_ARM_V4BX requires no computation. It marks the
location of an ARMv4 branch exchange instruction.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
In fully self-contained deployments it may be desirable to build iPXE
with an empty CROSSCERT source to avoid talking to external services.
Add an explicit check for this case and make validator_start_download
fail immediately if the base URI is empty.
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some HP BIOSes (observed with a Z840) seem to attempt to connect our
drivers in the middle of our call to DisconnectController(). The
precise chain of events is unclear, but the symptom is that we see
several calls to our Supported() and Start() methods, followed by a
system lock-up.
Work around this dubious BIOS behaviour by explicitly failing calls to
our Start() method while we are in the middle of attempting to
disconnect drivers.
Reported-by: Jordan Wright <jordan.m.wright@disney.com>
Debugged-by: Adrian Lucrèce Céleste <adrianlucrececeleste@airmail.cc>
Debugged-by: Christian Nilsson <nikize@gmail.com>
Tested-by: Jordan Wright <jordan.m.wright@disney.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
When submitting binaries for UEFI Secure Boot signing, certain
known-dubious subsystems (such as 802.11 and NFS) must be excluded
from the build. Mark the directories containing these subsystems as
insecure, and allow the build target to include an explicit "security
flag" (a literal "-sb" appended to the build platform) to exclude
these source directories from the build process.
For example:
make bin-x86_64-efi-sb/ipxe.efi
will build iPXE with all code from the 802.11 and NFS subsystems
excluded from the build.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some UEFI BIOSes will deliberately break the implementation of
ConnectController() to return errors for devices that have been
"disabled" via the BIOS setup screen. (As an added bonus, such BIOSes
may return garbage EFI_STATUS values such as 0xff.)
Work around these broken UEFI BIOSes by ignoring failures and
continuing to attempt to connect any remaining handles.
Signed-off-by: Michael Brown <mcb30@ipxe.org>