Pretty much all physical machines and off-the-shelf virtual machines
will provide a functional PCI BIOS. We therefore default to using
only the PCI BIOS, with no fallback to an alternative mechanism if the
PCI BIOS fails.
AWS EC2 provides the opportunity to experience some exceptions to this
rule. For example, the t3a.nano instances in eu-west-1 have no
functional PCI BIOS at all. As of commit 83516ba ("[cloud] Use
PCIAPI_DIRECT for cloud images") we therefore use direct Type 1
configuration space accesses in the images built and published for use
in the cloud.
Recent experience has discovered yet more variation in AWS EC2
instances. For example, some of the metal instance types have
multiple PCI host bridges and the direct Type 1 accesses therefore
see only a subset of the PCI devices.
Attempt to accommodate future such variations by making the PCI I/O
API selectable at runtime and choosing ECAM (if available), falling
back to the PCI BIOS (if available), then finally falling back to
direct Type 1 accesses.
This is implemented as a dedicated PCIAPI_CLOUD API, rather than by
having the PCI core select a suitable API at runtime (as was done for
timers in commit 302f1ee ("[time] Allow timer to be selected at
runtime"). The common case will remain that only the PCI BIOS API is
required, and we would prefer to retain the optimisations that come
from inlining the configuration space accesses in this common case.
Cloud images are (at present) disk images rather than ROM images, and
so the increased code size required for this design approach in the
PCIAPI_CLOUD case is acceptable.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The DHCP service in EC2 has been observed to occasionally stop
responding for bursts of several seconds. This can easily result in a
failed boot, since the current cloud boot script will attempt DHCP
only once.
Work around this problem by retrying DHCP in a fairly tight cycle
within the cloud boot script, and falling back to a reboot after
several failed DHCP attempts.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Most EFI firmware builds (including those found on ARM64 instances in
AWS EC2) will already send console output to the serial port.
Do not enable direct serial console output in EFI builds using
CONFIG=cloud.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The version of SeaBIOS found on some AWS EC2 instances (observed with
t3a.nano in eu-west-1) has no support for the INT 1A PCI BIOS calls.
Bring config/ioapi.h into the named-configuration set of headers, and
specify the use of PCIAPI_DIRECT for CONFIG=cloud, to work around the
missing PCI BIOS support.
Switching to a different named configuration will now unfortunately
cause an almost complete rebuild of iPXE. As described in commit
c801cb2 ("[build] Allow for named configurations at build time"), this
is the reason why config/ioapi.h was not originally in the
named-configuration set of header files.
This rebuild cost is acceptable given that build times are
substantially faster now than seven years ago, and that very few
people are likely to be switching named configurations on a regular
basis.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some problems arise only when running on a specific CPU type (e.g.
non-functional timer interrupts as observed in Azure AMD instances).
Include the CPU vendor and model within the sample cloud boot scripts,
to assist in debugging such problems.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
For some unspecified "security" reason, the Google Compute Engine
metadata server will refuse any requests that do not include the
non-standard HTTP header "Metadata-Flavor: Google".
Attempt to autodetect such requests (by comparing the hostname against
"metadata.google.internal"), and add the "Metadata-Flavor: Google"
header if applicable.
Enable this feature in the CONFIG=cloud build, and include a sample
embedded script allowing iPXE to boot from a script configured as
metadata via e.g.
# Create shared boot image
make bin/ipxe.usb CONFIG=cloud EMBED=config/cloud/gce.ipxe
# Configure per-instance boot script
gcloud compute instances add-metadata <instance> \
--metadata-from-file ipxeboot=boot.ipxe
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add a named CONFIG=cloud configuration, which enables console types
useful for obtaining output from virtual machines in public clouds
such as AWS EC2.
An image suitable for use in AWS EC2 can be built using
make bin/ipxe.usb CONFIG=cloud EMBED=config/cloud/aws.ipxe
The embedded script will direct iPXE to download and execute the EC2
"user-data" file, which is always available to an EC2 VM via the URI
http://169.254.169.254/latest/user-data (regardless of the VPC
networking settings). The boot can therefore be controlled by
modifying the per-instance user data, without having to modify the
boot disk image.
Console output can be obtained via syslog (with a syslog server
configured in the user-data script), via the AWS "System Log" (after
the instance has been stopped), or as a last resort from the log
partition on the boot disk.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown