On Thu, Jul 14, 2016 at 1:45 AM, Yubin Ruan <ablacktsh...@gmail.com> wrote:
> On Wed, Jul 13, 2016 at 7:33 PM, Yubin Ruan <ablacktsh...@gmail.com >> <mailto:ablacktsh...@gmail.com>> wrote: >> >> Hi, >> I got some question about the AT directive in linker script. I have >> post this question to binutils{at}sourceware.org >> <http://sourceware.org> with no reply. >> >> Hopefully someone can help me out. >> >> After some searching and asking, I finally know that the AT directive >> tell the linker about LMA of a section. >> >> For example there is some linker script like this: >> >> SECTIONS >> { >> . = 0X80100000; >> .text : AT(0x100000) { >> *(.text .stub .text.* .gnu.linkonce.t.*) >> } >> >> ... blah blah ... >> } >> >> Now 0x8010000 is a VMA, and 0x100000 is a LMA. >> >> My question is, is LMA the same as the physical address in a ELF >> program header ? A typical ELF declaration would be something like >> this: >> >> typedef struct >> { >> Elf32_Word p_type; /* Segment type */ >> Elf32_Off p_offset; /* Segment file offset */ >> Elf32_Addr p_vaddr; /* Segment virtual address */ >> Elf32_Addr p_paddr; /* Segment physical address >> */ >> Elf32_Word p_filesz; /* Segment size in file */ >> Elf32_Word p_memsz; /* Segment size in memory */ >> Elf32_Word p_flags; /* Segment flags */ >> Elf32_Word p_align; /* Segment alignment */ >> } Elf32_Phdr; >> >> Is LMA just **p_paddr** in the program header? >> >> ...snip... > Thank you for replying. I think I understand what you mean. > But I still want the answer to my question, that is, is LMA just > **p_paddr** in the program header? > I'm pretty sure that's the case. There are actually 2 sets of headers. You can use: objdump -p foo.elf to view the "private" headers which shows you the p_vaddr and p_paddr fields. And you can use objdump -h foo.elf to view the section headers. Here's some example output for a typical embedded program: 2216 >objdump -p firmware.elf firmware.elf: file format elf32-little Program Header: LOAD off 0x00008000 vaddr 0x08000000 paddr 0x08000000 align 2**15 filesz 0x0000288c memsz 0x0000288c flags r-x LOAD off 0x00010000 vaddr 0x08020000 paddr 0x08020000 align 2**15 filesz 0x00040470 memsz 0x00040470 flags r-x LOAD off 0x00058000 vaddr 0x20000000 paddr 0x08060470 align 2**15 filesz 0x00000108 memsz 0x000064f0 flags rw- LOAD off 0x0005e4f0 vaddr 0x200064f0 paddr 0x08060578 align 2**15 filesz 0x00000000 memsz 0x00004000 flags rw- LOAD off 0x0005a4f0 vaddr 0x2000a4f0 paddr 0x08060578 align 2**15 filesz 0x00000000 memsz 0x00000800 flags rw- 2217 >objdump -h firmware.elf firmware.elf: file format elf32-little Sections: Idx Name Size VMA LMA File off Algn 0 .isr_vector 0000288c 08000000 08000000 00008000 2**2 CONTENTS, ALLOC, LOAD, READONLY, CODE 1 .text 00040470 08020000 08020000 00010000 2**2 CONTENTS, ALLOC, LOAD, READONLY, CODE 2 .data 00000108 20000000 08060470 00058000 2**2 CONTENTS, ALLOC, LOAD, DATA 3 .bss 000063e8 20000108 08060578 00058108 2**2 ALLOC 4 .heap 00004000 200064f0 08060578 0005e4f0 2**0 ALLOC 5 .stack 00000800 2000a4f0 08060578 0005a4f0 2**0 ALLOC 6 .ARM.attributes 00000037 00000000 00000000 00058108 2**0 CONTENTS, READONLY 7 .comment 000000e0 00000000 00000000 0005813f 2**0 CONTENTS, READONLY -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com
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