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
