[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.
[i386] Add data32 prefixes to all lgdt/lidt instructions
With a 16-bit operand, lgdt/lidt will load only a 24-bit base address,
ignoring the high-order bits. This meant that we could fail to fully
restore the GDT across a call into gPXE, if the GDT happened to be
located above the 16MB mark.
Not all of our lgdt/lidt instructions require a data32 prefix (for
example, reloading the real-mode IDT can never require a 32-bit base
address), but by adding them everywhere we will hopefully not forget
the necessary ones in future.
[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.
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.
[libprefix] Add addr32 prefix required by older assemblers
Explicitly state that we are using 32-bit addressing in 16-bit code.
GNU as 2.15 (FreeBSD/amd64 7-STABLE) got confused that 32-bit registers
are used in the code that was declared as 16-bit. Add explicit modifier
'addr32' to make assembler happy.
Signed-off-by: Eygene Ryabinkin <rea-fbsd@codelabs.ru>
[prefix] Cope with image source addresses outside base memory
When PMM is used, the gPXE image source will no longer be in base memory.
Decompression of .text16 and .data16 can therefore no longer be done in
real mode.
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.
Don't trash the %ecx value returned by relocate(). This was causing
us to round down the size for the relocation copy to the nearest 64kB
(+0x10 bytes); this just happened to work on most machines because the
last 64kB of the image is all-zeroes anyway (it's the .bss).
Add infrastructure to support access to .data16 (and .text16) variables
from protected-mode code.
Set up %ds to point to .data16 in prot_to_real, so that code specified
via REAL_EXEC() and friends can access variables in .data16.
Move most real-mode librm variables from .text16 to .data16.
Michael Brown