This commit implements GDB over UDP. Using UDP is more complex than
serial and has required some restructuring.
The GDB stub is now built using one or both of GDBSERIAL and GDBUDP
config.h options.
To enter the debugger, execute the gPXE shell command:
gdbstub <transport> [<options>...]
Where <transport> is "serial" or "udp". For "udp", the name of a
configured network device is required:
gdbstub udp net0
The GDB stub listens on UDP port 43770 by default.
Return the most appropriate of EACCES, EPERM, ENODEV, ENOTSUP, EIO or
EINVAL depending on the exact error returned by the target, rather than
just always returning EPERM.
Also, ensure that error strings exist for these errors.
PXE is a catch-all image format with no signature checks. If an
unsupported image file is loaded, it will be treated as a PXE image. In
most cases, the image will be too large to be loaded as a PXE image (which
has to fit in base memory), so the error returned to the user will be that
the segment could not fit within the memory region.
Add an explicit check to pxe_image.c to reject images larger than base
memory with ENOEXEC.
Add ENOEXEC to the error string table.
Allow for settings to be described by something other than a DHCP option
tag if desirable. Currently used only for the MAC address setting.
Separate out fake DHCP packet creation code from dhcp.c to fakedhcp.c.
Remove notion of settings from dhcppkt.c.
Rationalise dhcp.c to use settings API only for final registration of the
DHCP options, rather than using {store,fetch}_setting throughout.
Add the notion of the settings hierarchy, complete with
register/unregister routines.
Rename set->store and get->fetch to avoid naming conflicts with get/put
as used in reference counting.
Add the concept of an abstract configuration setting, comprising a (DHCP)
tag value and an associated byte sequence.
Add the concept of a settings namespace.
Add functions for extracting string, IPv4 address, and signed and
unsigned integer values from configuration settings (analogous to
dhcp_snprintf(), dhcp_ipv4_option(), etc.).
Update functions for parsing and formatting named/typed options to work
with new settings API.
Update NVO commands and config UI to use new settings API.
show_setting() and related functions now return an "actual length" in the
style of snprintf(). This is to allow consumers to allocate buffers large
enough to hold the formatted setting.
tcpip_tx(). This avoids the irritating wait when you accidentally type
"kernel pxelinux.0" before bringing up the network interface.
Add ENETUNREACH to strerror()'s list.
Stefan Hajnoczi