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Re: [Qemu-devel] [PATCH] multiboot: mh_load_end_addr and mh_bss_end_addr
From: |
Göran Weinholt |
Subject: |
Re: [Qemu-devel] [PATCH] multiboot: mh_load_end_addr and mh_bss_end_addr may be zero |
Date: |
Wed, 01 Feb 2012 01:44:43 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) |
Kevin Wolf <address@hidden> writes:
> Am 23.01.2012 13:49, schrieb Göran Weinholt:
>> There are two special cases in the address fields of the multiboot
>> format. If mh_load_end_addr is zero then the whole image file should
>> be loaded and if mh_bss_end_addr is zero then there is no bss segment.
>> With this change it is again possible to boot kernels where these
>> fields are zero.
>>
>> Signed-off-by: Göran Weinholt <address@hidden>
>> Tested-by: Alexander Graf <address@hidden>
>> ---
>> hw/multiboot.c | 15 ++++++++++++++-
>> 1 files changed, 14 insertions(+), 1 deletions(-)
>>
>> diff --git a/hw/multiboot.c b/hw/multiboot.c
>> index b4484a3..db28328 100644
>> --- a/hw/multiboot.c
>> +++ b/hw/multiboot.c
>> @@ -202,10 +202,23 @@ int load_multiboot(void *fw_cfg,
>> uint32_t mh_bss_end_addr = ldl_p(header+i+24);
>> mh_load_addr = ldl_p(header+i+16);
>> uint32_t mb_kernel_text_offset = i - (mh_header_addr -
>> mh_load_addr);
>> - uint32_t mb_load_size = mh_load_end_addr - mh_load_addr;
>> + uint32_t mb_load_size;
>> +
>> + /* A load end address of zero indicates that the whole file
>> + * should be loaded. */
>> + if (!mh_load_end_addr) {
>> + mh_load_end_addr = kernel_file_size + mh_load_addr;
>
> This is only right if the OS image starts at offset 0 in the image file.
> IIUC, in the general case it starts at byte i - (mh_header_addr -
> mh_load_addr), so you need to subtract this from kernel_file_size.
I think you're right. It would be good if someone could have a look at
fixing the patch. I will not have time to do it myself. Please Cc me so
that I can test it on my own kernel images.
Regards,
--
Göran Weinholt <address@hidden>
"The bus! I have missed the bus! I have become... tardy!" -- Dexter's Lab