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/share/man/man9/bios.9

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  1.\" $FreeBSD$
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  3.\" Copyright (c) 1997 Michael Smith
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 27.Dd August 9, 2005
 28.Dt BIOS 9
 29.Os
 30.Sh NAME
 31.Nm bios_sigsearch ,
 32.Nm bios32_SDlookup ,
 33.Nm bios32 ,
 34.Nm bios_oem_strings
 35.Nd interact with PC BIOS
 36.Sh SYNOPSIS
 37.In sys/param.h
 38.In vm/vm.h
 39.In vm/pmap.h
 40.In machine/param.h
 41.In machine/pmap.h
 42.In machine/pc/bios.h
 43.Ft uint32_t
 44.Fn bios_sigsearch "uint32_t start" "u_char *sig" "int siglen" "int paralen" "int sigofs"
 45.Ft int
 46.Fn bios32_SDlookup "struct bios32_SDentry *ent"
 47.Ft int
 48.Fn bios32 "struct bios_regs *br" "u_int offset" "u_short segment"
 49.Fn BIOS_PADDRTOVADDR "addr"
 50.Fn BIOS_VADDRTOPADDR "addr"
 51.Vt extern struct bios32_SDentry PCIbios ;
 52.Vt extern struct SMBIOS_table SMBIOStable ;
 53.Vt extern struct DMI_table DMItable ;
 54.Ft int
 55.Fn bios_oem_strings "struct bios_oem *oem" "u_char *buffer" "size_t maxlen"
 56.Bd -literal
 57struct bios_oem_signature {
 58        char * anchor;          /* search anchor string in BIOS memory */
 59        size_t offset;          /* offset from anchor (may be negative) */
 60        size_t totlen;          /* total length of BIOS string to copy */
 61};
 62struct bios_oem_range {
 63        u_int from;             /* shouldn't be below 0xe0000 */
 64        u_int to;               /* shouldn't be above 0xfffff */
 65};
 66struct bios_oem {
 67        struct bios_oem_range range;
 68        struct bios_oem_signature signature[];
 69};
 70.Ed
 71.Sh DESCRIPTION
 72These functions provide a general-purpose interface for dealing with
 73the BIOS functions and data encountered on x86 PC-architecture systems.
 74.Bl -tag -width 20n
 75.It Fn bios_sigsearch
 76Searches the BIOS address space for a service signature, usually an
 77uppercase ASCII sequence surrounded by underscores.
 78The search begins at
 79.Fa start ,
 80or at the beginning of the BIOS if
 81.Fa start
 82is zero.
 83.Fa siglen
 84bytes of the BIOS image and
 85.Fa sig
 86are compared at
 87.Fa sigofs
 88bytes offset from the current location.
 89If no match is found, the
 90current location is incremented by
 91.Fa paralen
 92bytes and the search repeated.
 93If the signature is found, its effective
 94physical address is returned.
 95If no signature is found, zero is returned.
 96.It Fn bios_oem_strings
 97Searches a given BIOS memory range for one or more strings,
 98and composes a printable concatenation of those found.
 99The routine expects a structure describing the BIOS address
100.Fa range
101(within
102.Li 0xe0000
103-
104.Li 0xfffff ) ,
105and a {
106.Dv NULL , Li 0 , 0
107} -terminated array of
108.Vt bios_oem_signature
109structures which define the
110.Va anchor
111string, an
112.Va offset
113from the beginning of the match (which may be negative), and
114.Va totlen
115number of bytes to be collected from BIOS memory starting at that offset.
116Unmatched anchors are ignored, whereas matches are copied from BIOS memory
117starting at their corresponding
118.Vt offset
119with unprintable characters being replaced with space, and consecutive spaces
120being suppressed.
121This composed string is stored in
122.Fa buffer
123up to the given
124.Fa maxlen
125bytes (including trailing
126.Ql \e0 ,
127and any trailing space suppressed).
128If an error is encountered, i.e.\& trying to read out of said BIOS range,
129other invalid input, or
130.Fa buffer
131overflow, a negative integer is returned, otherwise the
132length of the composed string is returned.
133In particular, a return
134value of 0 means that none of the given anchor strings were found in
135the specified BIOS memory range.
136.It Fn BIOS_VADDRTOPADDR
137Returns the effective physical address which corresponds to the kernel
138virtual address
139.Fa addr .
140.It Fn BIOS_PADDRTOVADDR
141Returns the kernel virtual address which corresponds to the effective
142physical address
143.Fa addr .
144.It SMBIOStable
145If not NULL, points to a
146.Ft struct SMBIOS_table
147structure containing information read from the System Management BIOS table
148during system startup.
149.It DMItable
150If not NULL, points to a
151.Ft struct DMI_table
152structure containing information read from the Desktop Management Interface
153parameter table during system startup.
154.El
155.Sh BIOS32
156At system startup, the BIOS is scanned for the BIOS32 Service Directory
157(part of the PCI specification), and the existence of the directory is
158recorded.
159This can then be used to locate other services.
160.Bl -tag -width 20n
161.It Fn bios32_SDlookup
162Attempts to locate the BIOS32 service matching the 4-byte identifier
163passed in the
164.Fa ident
165field of the
166.Fa ent
167argument.
168.It Fn bios32
169Calls a bios32 function.
170This presumes that the function is capable of
171working within the kernel segment (normally the case).
172The virtual address
173of the entrypoint is supplied in
174.Fa entry
175and the register arguments to the function are supplied in
176.Fa args .
177.It PCIbios
178If not NULL, points to a
179.Ft struct bios32_SDentry
180structure describing the PCI BIOS entrypoint which was found during system
181startup.
182.El