memory detection

diff --git a/src/boot/boot2.s b/src/boot/boot2.s
index 15b1cb1..59096ac 100644 (file)
--- a/src/boot/boot2.s
+++ b/src/boot/boot2.s
@@ -557,19 +557,61 @@ kbc_wait_write:
 numbuf: .space 16
 
 
-       # sets the carry flag on failure
 detect_memory:
+       mov $memdet_e820_msg, %esi
+       call putstr
+       call detect_mem_e820
+       jnc memdet_done
+       mov $rdfail_msg, %esi
+       call putstr
+
+       mov $memdet_e801_msg, %esi
+       call putstr
+       call detect_mem_e801
+       jnc memdet_done
+       mov $rdfail_msg, %esi
+       call putstr
+
+       mov $memdet_88_msg, %esi
+       call putstr
+       call detect_mem_88
+       jnc memdet_done
+       mov $rdfail_msg, %esi
+       call putstr
+
+       # just panic...
+       mov $memdet_fail_msg, %esi
+       call putstr
+0:     hlt
+       jmp 0b
+
+memdet_done:
+       mov $rdok_msg, %esi
+       call putstr
+       ret
+
+memdet_fail_msg: .ascii "Failed to detect available memory!\n"
+                .ascii "Please file a bug report: https://github.com/jtsiomb/pcboot/issues\n"
+                .asciz " or contact me through email: nuclear@member.fsf.org\n"
+memdet_e820_msg: .asciz "Detecting RAM (BIOS 15h/0xe820)... "
+memdet_e801_msg: .asciz "Detecting RAM (BIOS 15h/0xe801)... " 
+memdet_88_msg:  .asciz "Detecting RAM (BIOS 15h/0x88, max 64mb)... "
+
+       # detect extended memory using BIOS call 15h/e820
+detect_mem_e820:
+       movl $0, boot_mem_map_size
+
        mov $buffer, %edi
        xor %ebx, %ebx
        mov $0x534d4150, %edx
 
-memdet_looptop:
+e820_looptop:
        mov $0xe820, %eax
        mov $24, %ecx
        int $0x15
-       jc memdet_fail
+       jc e820_fail
        cmp $0x534d4150, %eax
-       jnz memdet_fail
+       jnz e820_fail
 
        mov buffer, %eax
        mov $boot_mem_map, %esi
@@ -579,47 +621,111 @@ memdet_looptop:
 
        # only care for type 1 (usable ram), otherwise ignore
        cmpl $1, 16(%edi)
-       jnz memdet_skip
+       jnz e820_skip
 
        # skip areas with 0 size (also clamp size to 4gb)
        # test high 32bits
        cmpl $0, 12(%edi)
-       jz memdet_highzero
+       jz e820_highzero
        # high part is non-zero, make low part ffffffff
        xor %eax, %eax
        not %eax
        jmp 0f
 
-memdet_highzero:
+e820_highzero:
        # if both high and low parts are zero, ignore
        mov 8(%edi), %eax
        cmpl $0, %eax
-       jz memdet_skip
+       jz e820_skip
 
 0:     mov %eax, 4(%esi,%ebp,8)
        incl boot_mem_map_size
 
-memdet_skip:
+e820_skip:
        # terminate the loop if ebx was reset to 0
        cmp $0, %ebx
-       jz memdet_done
-       jmp memdet_looptop
+       jz e820_done
+       jmp e820_looptop
 
-memdet_done:
+e820_done:
+       clc
        ret
 
-memdet_fail:
+e820_fail:
        # if size > 0, then it's not a failure, just the end
        cmpl $0, boot_mem_map_size
-       jnz memdet_done
+       jnz e820_done
 
-       # just panic...
-       mov $memdet_fail_msg, %esi
-       call putstr
-0:     hlt
-       jmp 0b
+       stc
+       ret
+
+
+       # detect extended memory using BIOS call 15h/e801
+detect_mem_e801:
+       mov $boot_mem_map, %esi
+       mov boot_mem_map_size, %ebp
+       movl $0, (%ebp)
+
+       xor %cx, %cx
+       xor %dx, %dx
+       mov $0xe801, %ax
+       int $0x15
+       jc e801_fail
+
+       cmp $0, %cx
+       jnz 0f
+       cmp $0, %ax
+       jz e801_fail
+       mov %ax, %cx
+       mov %bx, %dx
+
+0:     movl $0x100000, (%esi)
+       movzx %cx, %eax
+       # first size is in KB, convert to bytes
+       shl $10, %eax
+       mov %eax, 4(%esi)
+       cmp $0, %dx
+       incl boot_mem_map_size
+       jz e801_done
+       movl $0x1000000, 8(%esi)
+       movzx %dx, %eax
+       # second size is in 64kb blocks, convert to bytes
+       shl $16, %eax
+       mov %eax, 12(%esi)
+       incl boot_mem_map_size
+e801_done:
+       clc
+       ret
+e801_fail:
+       stc
+       ret
+
+detect_mem_88:
+       # reportedly some BIOS implementations fail to clear CF on success
+       clc
+       mov $0x88, %ah
+       int $0x15
+       jc x88_fail
+
+       cmp $0, %ax
+       jz x88_fail
+
+       # ax has size in KB, convert to bytes in eax
+       and $0xffff, %eax
+       shl $10, %eax
+
+       mov $boot_mem_map, %esi
+       movl $0x100000, (%esi)
+       mov %eax, 4(%esi)
+
+       movl $1, boot_mem_map_size
+       clc
+       ret
+
+x88_fail:
+       stc
+       ret
 
-memdet_fail_msg: .asciz "Failed to detect available memory!\n"
 
        .global boot_mem_map_size
 boot_mem_map_size: .long 0