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Switch off trailing 0xff optimisation when writing memory lists to file

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It is crucial not to skip empty flash memory: otherwise the output file
cannot distinguish between flash having been deliberately dropped by the
user or it having been empty.
This commit is contained in:
Stefan Rueger
2024-06-17 12:41:02 +01:00
parent 0be19da627
commit 9ab4aac045
1 changed files with 18 additions and 2 deletions
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20
src/update.c
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@@ -379,7 +379,7 @@ int update_dryrun(const AVRPART *p, UPDATE *upd) {
}
// Whether a memory should be backup-ed: exclude sub-memories
static int backup_mem(const AVRPART *p, const AVRMEM *mem) {
static int is_backup_mem(const AVRPART *p, const AVRMEM *mem) {
return mem_is_in_flash(mem)? mem_is_flash(mem):
mem_is_in_sigrow(mem)? mem_is_sigrow(mem):
mem_is_in_fuses(mem)? mem_is_fuses(mem) || !avr_locate_fuses(p):
@@ -423,7 +423,7 @@ int do_op(const PROGRAMMER *pgm, const AVRPART *p, const UPDATE *upd, enum updat
s = str_trim(s);
if(str_eq(s, "all")) {
for(LNODEID lm = lfirst(p->mem); lm; lm = lnext(lm))
if(backup_mem(p, (m = ldata(lm))))
if(is_backup_mem(p, (m = ldata(lm))))
umemlist[ns++] = m;
} else if(!*s) { // Ignore empty list elements
} else {
@@ -466,6 +466,21 @@ int do_op(const PROGRAMMER *pgm, const AVRPART *p, const UPDATE *upd, enum updat
goto error;
}
if(umemlist) {
/*
* Writing to all memories or a list of memories. It is crucial not to
* skip empty flash memory: otherwise the output file cannot distinguish
* between flash having been deliberately dropped by the user or it
* having been empty. Therefore the code switches temporarily off
* trailing 0xff optimisation. In theory, the output file could only
* store those pages that are non-empty for a paged memory, and if it was
* all empty, store only the first empty page to indicate the memory was
* selected. However, file space on a PC is cheap and fast; the main use
* case for saving "all" memory is a backup, and AVRDUDE does not want to
* rely on the uploader to know that the backup file requires the paged
* memories to be erased first, so the code goes the full hog.
*/
int dffo = cx->avr_disableffopt;
cx->avr_disableffopt = 1;
pmsg_info("reading %s memor%s ...\n",
ns==1? avr_mem_name(p, umemlist[0]): "multiple", ns==1? "y": "ies");
int nn = 0;
@@ -498,6 +513,7 @@ int do_op(const PROGRAMMER *pgm, const AVRPART *p, const UPDATE *upd, enum updat
rc = fileio_segments(FIO_WRITE, upd->filename, upd->format, p, mem, nn, seglist);
else
pmsg_notice("empty memory, resulting file has no contents\n");
cx->avr_disableffopt = dffo;
} else { // Regular file
pmsg_info("reading %s memory ...\n", mem_desc);
if(mem->size > 32 || verbose > 1)