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Re: [Qemu-devel] [Qemu-arm] [PATCH v4 5/6] loader: Implement .hex file l
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [Qemu-arm] [PATCH v4 5/6] loader: Implement .hex file loader |
Date: |
Mon, 13 Aug 2018 16:56:22 +0100 |
User-agent: |
Mutt/1.10.0 (2018-05-17) |
On Fri, Aug 10, 2018 at 02:00:44AM -0300, Philippe Mathieu-Daudé wrote:
> On 08/03/2018 11:47 AM, Stefan Hajnoczi wrote:
> > + parser->rom_start_address = parser->next_address_to_write;
> > + parser->current_rom_index = 0;
> > + break;
> > +
> > + case START_SEG_ADDR_RECORD:
> > + 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];
>
> Can you add a qtest for this case?
> For the HEX loader I understand the specs as this is the same parsing as
> the START_LINEAR_ADDR_RECORD case; so I disagree with data[0] and
> data[1] shifts.
x86 real-mode CS:IP addressing means (CS << 4) + IP. It produces 24-bit
addresses on 80286 and later. This is not the same as
START_LINEAR_ADDR_RECORD.
GNU bfd implements it as follows:
abfd->start_address += (HEX4 (buf) << 4) + HEX4 (buf + 4);
https://sourceware.org/git/?p=binutils.git;a=blob;f=bfd/ihex.c;h=09f756a1c2c11e57c5da15a6ff96491275575b86;hb=HEAD#l415
Thanks for commenting on this, I had written (CS << 4) | IP instead of
(CS << 4) + IP. This will be fixed in the next revision.
> This is different for the consumer (i386 expects 2 16-bit registers but
> HexParser->start_addr is a hwaddr, used as a single (at least) 32-bit
> register.
I think you're saying that on x86 the guest CS:IP registers should be
set. This loader is never called from hw/i386/ so it doesn't matter at
this time.
GNU bfd uses START_SEG_ADDR_RECORD records on non-x86 architectures
where there are no segment registers and that's where we've encountered
them.
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- Re: [Qemu-devel] [PATCH v4 3/6] loader: extract rom_free() function, (continued)
[Qemu-devel] [PATCH v4 6/6] Add QTest testcase for the Intel Hexadecimal, Stefan Hajnoczi, 2018/08/03