Ping! On Tue, Aug 26, 2014 at 05:20:54PM +0530, Senthil Kumar Selvaraj wrote: > On Mon, Aug 11, 2014 at 04:26:22PM +0200, Joerg Wunsch wrote: > > As Senthil Kumar Selvaraj wrote: > > > > > I figured it's easier and less error-prone to embed this information > > > here and then consume it everywhere else. I have a patch for > > > binutils, for example, that uses the information in the note section > > > to print percentage of memory used - like what the WinAVR port of > > > avr-size does, but without the hardcoding. > > > > I like that idea much more than Eric Weddington's hack. > > > > I think the AVR is ultimately not the only device which might this be > > a concern of; all flash-based controllers can probably benefit from > > it. Thinking a little more about the layout of that device > > information (so it can e.g. be applied to all flash-based ARM > > controllers as well) would IMHO much increase the likelihood of this > > being accepted as a general solution by the binutils folks. After > > all, Atmel could go ahead, and apply it to their own ARM devices as > > a first example. ;-) > > Yes, it makes sense to make it as general as possible. > > > > > + .section .note.gnu.avr.deviceinfo, "", @note > > > +#define NOTE_NAME "AVR" > > > +#ifdef __AVR_DEVICE_NAME__ > > > + #define DEVICE_NAME STR(__AVR_DEVICE_NAME__) > > > +#else > > > + #define DEVICE_NAME "" > > > +#endif > > > + .long .L__note_name_end - .L__note_name_start > > > + .long .L__desc_end - .L__desc_start > > > + .long 1 ; Type 1 - this is the only known note type for AVR. > > > +.L__note_name_start: > > > + .asciz NOTE_NAME > > > +.L__note_name_end: > > > +.L__desc_start: > > > + .long .L__device_name_end - .L__device_name_start > > > +.L__device_name_start: > > > + .asciz DEVICE_NAME > > > +.L__device_name_end: > > > +#ifdef PROGMEM_SIZE > > > + .long PROGMEM_SIZE > > > +#elif FLASHEND > 0 > > > + .long FLASHEND + 1 > > > +#else > > > + .long FLASHEND > > > +#endif > > > +#ifdef RAMSIZE > > > + .long RAMSIZE > > > +#elif RAMEND > 0 > > > + .long RAMEND - RAMSTART + 1 > > > +#else > > > + .long RAMEND > > > +#endif > > > +#ifdef EEPROM_SIZE > > > + .long EEPROM_SIZE > > > +#elif E2END > 0 > > > + .long E2END + 1 > > > +#else > > > + .long E2END > > > +#endif > > > +.L__desc_end: > > > + .balign 4 > > > + > > > > Few things come to mind: > > > > * Start out with those parts of the information that have a fixed > > size, i.e. the sizes of the memory regions, and move the variable > > parts behind. That way, the initial part can be described as a C > > structure. > > > > * Wouldn't we also need start addresses? In particular, if you think > > beyond the horizon towards ARMs, their flash usually doesn't start > > at 0, but even for the AVR, the RAM starts at a device-dependent > > address. Providing on the the size information without the start is > > not very useful. (OTOH, information that can already be derived > > from other sources in the ELF file doesn't need to be duplicated.) > > > > * For the strings, add an offset (or index) table. That way, in order > > to read the second string, you don't have to traverse the first one. > > Thus, the actual string array somewhat resembles an ELF string > > section. > > > > * Please add a patch that explains the layout in the documentation, > > too. > > How does the below patch look? Once you guys find it ok, I'll follow it > up with a documentation patch. Note that the part above the > L__desc_start label (and the .balign directive at the end) are there as > per the ELF spec for a note section. > > diff --git avr-libc/crt1/gcrt1.S avr-libc/crt1/gcrt1.S > index 2d341a4..721573b 100644 > --- avr-libc/crt1/gcrt1.S > +++ avr-libc/crt1/gcrt1.S > @@ -304,3 +304,70 @@ __do_copy_data: > #endif /* __AVR_ASM_ONLY__ */ > ; .endfunc > > + .section .note.gnu.avr.deviceinfo, "", @note > +#define NOTE_NAME "AVR" > +#ifdef __AVR_DEVICE_NAME__ > + #define DEVICE_NAME STR(__AVR_DEVICE_NAME__) > +#else > + #define DEVICE_NAME "" > +#endif > + > + .long .L__note_name_end - .L__note_name_start > + .long .L__desc_end - .L__desc_start > + .long 1 ; Type 1 - this is the only known note type for AVR. > +.L__note_name_start: > + .asciz NOTE_NAME > +.L__note_name_end: > +.L__desc_start: > +#ifdef FLASHSTART > + .long FLASHSTART > +#else > + .long 0 > +#endif > +#ifdef PROGMEM_SIZE > + .long PROGMEM_SIZE > +#elif FLASHEND > 0 > + .long FLASHEND + 1 > +#else > + .long FLASHEND > +#endif > + .long RAMSTART > +#ifdef RAMSIZE > + .long RAMSIZE > +#elif RAMEND > 0 > + .long RAMEND - RAMSTART + 1 > +#else > + .long RAMEND > +#endif > +#ifdef E2START > + .long E2START > +#else > + .long 0 > +#endif > +#ifdef EEPROM_SIZE > + .long EEPROM_SIZE > +#elif E2END > 0 > + .long E2END + 1 > +#else > + .long E2END > +#endif > + /* String offsets table. > + Index 0 - Size of offset table in bytes > + Index 1 - Device name byte offset > + */ > +.L__stroffsettab_start: > +.long .L__stroffsettab_end - .L__stroffsettab_start /* Size of index table > in bytes */ > +.long .L__device_name_start - .L__strtab_start /* Byte offset of device name > */ > +.L__stroffsettab_end: > + /* String table for storing arbitrary strings. > + Offsets are stored in the string offset table above */ > +.L__strtab_start: > + .byte 0 > +.L__device_name_start: > + .asciz DEVICE_NAME > +.L__device_name_end: > + .byte 0 > +.L__strtab_end: > +.L__desc_end: > + .balign 4 > + > > > > > -- > > cheers, Joerg .-.-. --... ...-- -.. . DL8DTL > > > > http://www.sax.de/~joerg/ > > Never trust an operating system you don't have sources for. ;-) > > _______________________________________________ > AVR-libc-dev mailing list > AVR-libc-dev@nongnu.org > https://lists.nongnu.org/mailman/listinfo/avr-libc-dev
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