man/man9/bios.9

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.Dd August 9, 2005
.Dt BIOS 9
.Os
.Sh NAME
.Nm bios_sigsearch ,
.Nm bios32_SDlookup ,
.Nm bios32 ,
.Nm bios_oem_strings
.Nd interact with PC BIOS
.Sh SYNOPSIS
.In sys/param.h
.In vm/vm.h
.In vm/pmap.h
.In machine/param.h
.In machine/pmap.h
.In machine/pc/bios.h
.Ft u_int32_t
.Fn bios_sigsearch "u_int32_t start" "u_char *sig" "int siglen" "int paralen" "int sigofs"
.Ft int
.Fn bios32_SDlookup "struct bios32_SDentry *ent"
.Ft int
.Fn bios32 "struct bios_regs *br" "u_int offset" "u_short segment"
.Fn BIOS_PADDRTOVADDR "addr"
.Fn BIOS_VADDRTOPADDR "addr"
.Vt extern struct bios32_SDentry PCIbios ;
.Vt extern struct SMBIOS_table SMBIOStable ;
.Vt extern struct DMI_table DMItable ;
.Ft int
.Fn bios_oem_strings "struct bios_oem *oem" "u_char *buffer" "size_t maxlen"
.Bd -literal
struct bios_oem_signature {
        char * anchor;          /* search anchor string in BIOS memory */
        size_t offset;          /* offset from anchor (may be negative) */
        size_t totlen;          /* total length of BIOS string to copy */
};
struct bios_oem_range {
        u_int from;             /* shouldn't be below 0xe0000 */
        u_int to;               /* shouldn't be above 0xfffff */
};
struct bios_oem {
        struct bios_oem_range range;
        struct bios_oem_signature signature[];
};
.Ed
.Sh DESCRIPTION
These functions provide a general-purpose interface for dealing with
the BIOS functions and data encountered on x86 PC-architecture systems.
.Bl -tag -width 20n
.It Fn bios_sigsearch
Searches the BIOS address space for a service signature, usually an
uppercase ASCII sequence surrounded by underscores.
The search begins at
.Fa start ,
or at the beginning of the BIOS if
.Fa start
is zero.
.Fa siglen
bytes of the BIOS image and
.Fa sig
are compared at
.Fa sigofs
bytes offset from the current location.
If no match is found, the
current location is incremented by
.Fa paralen
bytes and the search repeated.
If the signature is found, its effective
physical address is returned.
If no signature is found, zero is returned.
.It Fn bios_oem_strings
Searches a given BIOS memory range for one or more strings,
and composes a printable concatenation of those found.
The routine expects a structure describing the BIOS address
.Fa range
(within
.Li 0xe0000
-
.Li 0xfffff ) ,
and a {
.Dv NULL , Li 0 , 0
} -terminated array of
.Vt bios_oem_signature
structures which define the
.Va anchor
string, an
.Va offset
from the beginning of the match (which may be negative), and
.Va totlen
number of bytes to be collected from BIOS memory starting at that offset.
Unmatched anchors are ignored, whereas matches are copied from BIOS memory
starting at their corresponding
.Vt offset
with unprintable characters being replaced with space, and consecutive spaces
being suppressed.
This composed string is stored in
.Fa buffer
up to the given
.Fa maxlen
bytes (including trailing
.Ql \e0 ,
and any trailing space surpressed).
If an error is encountered, i.e.\& trying to read out of said BIOS range,
other invalid input, or
.Fa buffer
overflow, a negative integer is returned, otherwise the
length of the composed string is returned.
In particular, a return
value of 0 means that none of the given anchor strings were found in
the specified BIOS memory range.
.It Fn BIOS_VADDRTOPADDR
Returns the effective physical address which corresponds to the kernel
virtual address
.Fa addr .
.It Fn BIOS_PADDRTOVADDR
Returns the kernel virtual address which corresponds to the effective
physical address
.Fa addr .
.It SMBIOStable
If not NULL, points to a
.Ft struct SMBIOS_table
structure containing information read from the System Management BIOS table
during system startup.
.It DMItable
If not NULL, points to a
.Ft struct DMI_table
structure containing information read from the Desktop Management Interface
parameter table during system startup.
.El
.Sh BIOS32
At system startup, the BIOS is scanned for the BIOS32 Service Directory
(part of the PCI specification), and the existence of the directory is
recorded.
This can then be used to locate other services.
.Bl -tag -width 20n
.It Fn bios32_SDlookup
Attempts to locate the BIOS32 service matching the 4-byte identifier
passed in the
.Fa ident
field of the
.Fa ent
argument.
.It Fn bios32
Calls a bios32 function.
This presumes that the function is capable of
working within the kernel segment (normally the case).
The virtual address
of the entrypoint is supplied in
.Fa entry
and the register arguments to the function are supplied in
.Fa args .
.It PCIbios
If not NULL, points to a
.Ft struct bios32_SDentry
structure describing the PCI BIOS entrypoint which was found during system
startup.
.El