Re: [Qemu-devel] [PATCH] loader: implement START_SEG_ADDR_RECORD

[Su Hang]

Sure, Thanks for remind me of this.
One thing I must point out, in current code logic, if "START_SEG_ADDR_RECORD"
occured multiple times, only the last one works. I don't know whether GNU
binutils would emit 'The Record' many times.

Best,
SU Hang


> -----Original Messages-----
> From: "Stefan Hajnoczi" <address@hidden>
> Sent Time: 2018-06-10 00:32:52 (Sunday)
> To: address@hidden
> Cc: "Su Hang" <address@hidden>, address@hidden, address@hidden, 
> address@hidden, address@hidden, "Stefan Hajnoczi" <address@hidden>
> Subject: [PATCH] loader: implement START_SEG_ADDR_RECORD
> 
> It turns out that GNU binutils emits START_SEG_ADDR_RECORD when the start
> address is within the first megabyte (< 0x100000).  Therefore we must
> handle this record type.
> 
> Originally we thought this record type was x86-specific, but binutils
> also emits it on non-x86 architectures.
> 
> Based-on: <address@hidden>
> Cc: Su Hang <address@hidden>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
> Su Hang: Feel free to squash this into the next revision of your hex
> loader patch.  Don't worry about the authorship information.
> 
>  hw/core/loader.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/core/loader.c b/hw/core/loader.c
> index 3c0202caa8..7843b487b2 100644
> --- a/hw/core/loader.c
> +++ b/hw/core/loader.c
> @@ -1423,8 +1423,14 @@ static int handle_record_type(HexParser *parser)
>          break;
>  
>      case START_SEG_ADDR_RECORD:
> -        /* TODO: START_SEG_ADDR_RECORD is x86-specific */
> -        return -1;
> +        if (line->byte_count != 4 && line->address != 0) {
> +            return -1;
> +        }
> +
> +        /* x86 16-bit CS:IP segmented addressing */
> +        *(parser->start_addr) = (((line->data[0] << 8) | line->data[1]) << 
> 4) |
> +                                (line->data[2] << 8) | line->data[3];
> +        break;
>  
>      case START_LINEAR_ADDR_RECORD:
>          if (line->byte_count != 4 && line->address != 0) {
> -- 
> 2.17.1