[romprefix] Change from opt-in to opt-out when booting via INT19
On non-BBS systems, we have to hook INT 19 in order to be able to boot
from the gPXE ROM at all. However, doing this unconditionally will
prevent the user from booting via any other devices.
Previously, the INT 19 entry point would prompt the user to press B in
order to boot from gPXE, which makes it impossible to perform an
unattended network boot. We now prompt the user to press N to skip
booting from gPXE, which allows for unattended operation.
This should be a better match for most real-world scenarios. Most
modern systems support BBS and so are unaffected by this change. Very
old (non-BBS) systems tend not to have PXE ROMs by default anyway; if
the user has added a gPXE ROM then they probably do want to boot from
the network. Newer non-BBS systems are essentially limited to IBM
servers, which will recapture the INT 19 vector anyway and implement
their own boot-ordering selection mechanism.
[i386] Free allocated base memory on exit, if possible
Code paths that automatically allocate memory from the FBMS at 40:13
should also free it, if possible.
Freeing this memory will not be possible if either
1. The FBMS has been modified since our allocation, or
2. We have not been able to unhook one or more BIOS interrupt vectors.
[romprefix] Use smaller PMM allocations if possible
The only way that PMM allows us to request a block in a region with
A20=0 is to ask for a block with an alignment of 2MB. Due to the PMM
API design, the only way we can do this is to ask for a block with a
size of 2MB.
Unfortunately, some BIOSes will hit problems if we allocate a 2MB
block. In particular, it may not be possible to enter the BIOS setup
screen; the BIOS setup code attempts a PMM allocation, fails, and
hangs the machine.
We now try allocating only as much as we need via PMM. If the
allocated block has A20=1, we free the allocated block, double the
allocation size, and try again. Repeat until either we obtain a block
with A20=0 or allocation fails. (This is guaranteed to terminate by
the time we reach an allocation size of 2MB.)
[romprefix] Add vendor branding facilities and guidelines
Some hardware vendors have been known to remove all gPXE-related
branding from ROMs that they build. While this is not prohibited by
the GPL, it is a little impolite.
Add a facility for adding branding messages via two #defines
(PRODUCT_NAME and PRODUCT_SHORT_NAME) in config/general.h. This
should accommodate all known OEM-mandated branding requirements.
Vendors with branding requirements that cannot be satisfied by using
PRODUCT_NAME and/or PRODUCT_SHORT_NAME should contact us so that we
can extended this facility as necessary.
[romprefix] Further sanity checks for the PCI 3 runtime segment address
This extends the sanity checks on the runtime segment address provided
in %bx, first implemented in commit 5600955.
We now allow the ROM to be placed anywhere above a000:0000 (rather
than c000:0000, as before), since this is the region allowed by the
PCI 3 spec. If the BIOS asks us to place the runtime image such that
it would overlap with the init-time image (which is explicitly
prohibited by the PCI 3 spec), then we assume that the BIOS is faulty
and ignore the provided runtime segment address.
Testing on a SuperMicro BIOS providing overlapping segment addresses
shows that ignoring the provided runtime segment address is safe to do
in these circumstances.
[romprefix] Sanity-check the runtime segment address for PCI 3
Some PCI 3 BIOSes seem to provide a garbage value in %bx, which should
contain the runtime segment address. Perform a basic sanity check: we
reject the segment if it is below the start of option ROM space. If
the sanity check fails, we assume that the BIOS was not expecting us
to be a PCI 3 ROM, and we just leave our image in situ.
Not fully understood, but it seems that the LMA of bss sections matters
for some newer binutils builds. Force all bss sections to have an LMA
at the end of the file, so that they don't interfere with other
sections.
The symptom was that objcopy -O binary -j .zinfo would extract the
.zinfo section from bin/xxx.tmp as a blob of the correct length, but
with zero contents. This would then cause the [ZBIN] stage of the
build to fail.
Also explicitly state that .zinfo(.*) sections have @progbits, in case
some future assembler or linker variant decides to omit them.
[i386] Simplify linker script and standardise linker-defined symbol names
Reduce the number of sections within the linker script to match the
number of practical sections within the output file.
Define _section, _msection, _esection, _section_filesz, _section_memsz,
and _section_lma for each section, replacing the mixture of symbols that
previously existed.
In particular, replace _text and _end with _textdata and _etextdata, to
make it explicit within code that uses these symbols that the .text and
.data sections are always treated as a single contiguous block.
[romprefix] Allow BANNER_TIMEOUT to control banners in romprefix.S
In particular, allow BANNER_TIMEOUT=0 to inhibit the prompt banners
altogether.
Ironically, this request comes from the same OEM that originally
required the prompts to be present during POST.
[romprefix] If we hook INT 19, prompt before attempting boot
On non-BBS systems we hook INT 19, since there is no other way we can
guarantee gaining control of the flow of execution. If we end up
doing this, prompt the user before attempting boot, since forcibly
capturing INT 19 is rather antisocial.
IBM's iSCSI Firmware Initiator checks the UNDIROMID pointer in the
!PXE structure that gets created by the UNDI loader. We didn't
previously fill this value in.
[romprefix] Add more diagnostic messages to ROM prefix
Include PMM allocation result in POST banner.
Include full product string in "starting execution" message.
Also mark ourselves as supporting DDIM in PnP header, for
completeness.
[romprefix] On a PCI3.0, non-BBS system, use the correct %cs for INT19
On a system that doesn't support BBS, we end up hooking INT19 to gain
control of the boot process. If the system is PCI3.0, we must take
care to use the runtime value for %cs, rather than the POST-time
value, otherwise we end up pointing INT19 to the temporary option ROM
POST scratch area.
Commit fd0aef9 introduced a typo that caused PMM detection to start at
paragraph 0xe00 rather than 0xe000. (Detection would still work, since it
would scan until it ran out of base memory, but it would end up scanning
an unnecessarily large portion of base memory.)
Spotted by Sebastian Herbszt <herbszt@gmx.de>.
[prefix] When we have to hook INT 19, chain to original handler if possible
When the BIOS doesn't support BBS, hooking INT 19 is the only way to add
ourselves as a boot device. If we have to do this, we should at least
try to chain to the original INT 19 vector if our boot fails.
Idea suggested by Andrew Schran <aschran@google.com>
[prefix] Prompt for entering gPXE shell during POST
The ROM prefix now prompts the user to enter the gPXE shell during POST;
this allows for configuring gPXE without needing to attempt to boot from
it. (It also slows down system boot by three seconds per gPXE ROM, but
hey.)
This is apparently a certain OEM's requirement for option ROMs.
Use BBS installation check to see if we need to hook INT19 even on a PnP
BIOS.
Verify that $PnP signature is paragraph-aligned; bochs/qemu BIOS provides
a dummy $PnP signature with no valid entry point, and deliberately
unaligns the signature to indicate that it is not properly valid.
Print message if INT19 is hooked.
Attempt to use PMM even if BBS check failed.
ROM initialisation vector now attempts to allocate a 2MB block using
PMM. If successful, it copies the ROM image to this block, then
shrinks the ROM image to allow for more option ROMs. If unsuccessful,
it leaves the ROM as-is.
ROM BEV now attempts to return to the BIOS, resorting to INT 18 only
if the BIOS stack has been corrupted.
Michael Brown