USB support

git-svn-id: svn://kolibrios.org@3520 a494cfbc-eb01-0410-851d-a64ba20cac60

kernel/trunk/detect/biosdisk.inc

@@ -7,6 +7,7 @@
 
 ; Detect all BIOS hard drives.
 ; diamond, 2008
+; Do not include USB mass storages. CleverMouse, 2013
 
         xor     cx, cx
         mov     es, cx
@@ -24,21 +25,40 @@ bdds:
         test    ah, ah
         jz      bddc
         inc     cx
+; We are going to call int 13h/func 48h, Extended get drive parameters.
+; The latest version of the EDD specification is 3.0.
+; There are two slightly incompatible variants for version 3.0;
+; original one from Phoenix in 1998, see e.g.
+; http://www.t10.org/t13/technical/d98120r0.pdf, and T13 draft,
+; http://www.t13.org/documents/UploadedDocuments/docs2004/d1572r3-EDD3.pdf
+; T13 draft addresses more possible buses, so it gives additional 8 bytes
+; for device path.
+; Most BIOSes follow Phoenix, but T13 version is also known to be used
+; (e.g. systems based on AMD Geode).
+; Fortunately, there is an in/out length field, so
+; it is easy to tell what variant was selected by the BIOS:
+; Phoenix-3.0 has 42h bytes, T13-3.0 has 4Ah bytes.
+; Note that 2.0 has 1Eh bytes, 1.1 has 1Ah bytes; both variants of 3.0 have
+; the same structure for first 1Eh bytes, compatible with previous versions.
+; Note also that difference between Phoenix-3.0 and T13-3.0 starts near the
+; end of the structure, so the current code doesn't even need to distinguish.
+; It needs, however, give at least 4Ah bytes as input and expect that BIOS
+; could return 42h bytes as output while still giving all the information.
         mov     ah, 48h
         push    ds
         push    es
         pop     ds
         mov     si, 0xA000
-        mov     word [si], 1Eh
+        mov     word [si], 4Ah
         mov     ah, 48h
         int     13h
         pop     ds
         jc      bddc2
-        inc     byte [es:0x907F]
         cmp     word [es:si], 1Eh
-        jb      bddl
+        jb      .noide
         cmp     word [es:si+1Ah], 0xFFFF
-        jz      bddl
+        jz      .noide
+        inc     byte [es:0x907F]
         mov     al, dl
         stosb
         push    ds
@@ -61,7 +81,15 @@ bdds:
         stosw
         pop     ds
         jmp     bddc2
-bddl:
+.noide:
+        cmp     word [es:si], 42h
+        jb      .nousb
+        cmp     word [es:si+28h], 'US'
+        jnz     .nousb
+        cmp     byte [es:si+2Ah], 'B'
+        jz      bddc2
+.nousb:
+        inc     byte [es:0x907F]
         mov     al, dl
         stosb
         xor     ax, ax