[flashrom] [PATCH] RFC: enable flashrom to write images of arbitrary size

[Peter Mamonov]

Hi David,

On Tue, Nov 08, 2016 at 11:22:56AM -0800, David Hendricks wrote:
> Hi Peter,
> Thanks for the patch! However, I suspect this will not be accepted
> since the size check is an important safety measure for the general
> use case.
> 
> In general layout files should be used for this sort of thing. The way
> we've gone about this in the chromium.org branch is to augment the -i
> syntax to allow the user to specify a region and corresponding file,
> and we also added a "--fast-verify" mode to only verify regions which
> were targeted. So for example you could do "flashrom -p <programmer>
> -l <layout_file> -i region:filename.bin --fast-verify --ignore-fmap
> -w" which will write filename.bin to the targeted region and verify
> only that region.
> 
> Details here: https://www.chromium.org/chromium-os/packages/cros-flashrom#TOC-Partial-Reads-and-Writes
> . LMK if this is any help.

Thanks for the tip! Looks like an ultimate solution. I'll try it and report the
results later.

Regards,
Peter

> 
> 
> 
> On Mon, Nov 7, 2016 at 1:00 PM, Peter Mamonov <pmamonov at gmail.com> wrote:
> > Flashrom restricts an image size to be equal to a ROM capacity. This is
> > inconvenient in case of large and slow ROM chips, when only part of the ROM
> > should be updated. This patch removes this restriction in a quick-and-dirty
> > manner.
> >
> > Signed-off-by: Peter Mamonov <pmamonov at gmail.com>
> > ---
> >  flashrom.c | 26 +++++++++++++++-----------
> >  1 file changed, 15 insertions(+), 11 deletions(-)
> >
> > diff --git a/flashrom.c b/flashrom.c
> > index d51a44c..f805e00 100644
> > --- a/flashrom.c
> > +++ b/flashrom.c
> > @@ -1255,30 +1255,30 @@ int read_buf_from_file(unsigned char *buf, unsigned long size,
> >
> >         if ((image = fopen(filename, "rb")) == NULL) {
> >                 msg_gerr("Error: opening file \"%s\" failed: %s\n", filename, strerror(errno));
> > -               return 1;
> > +               return -1;
> >         }
> >         if (fstat(fileno(image), &image_stat) != 0) {
> >                 msg_gerr("Error: getting metadata of file \"%s\" failed: %s\n", filename, strerror(errno));
> >                 fclose(image);
> > -               return 1;
> > +               return -1;
> >         }
> > -       if (image_stat.st_size != size) {
> > +       if (image_stat.st_size > size) {
> >                 msg_gerr("Error: Image size (%jd B) doesn't match the flash chip's size (%lu B)!\n",
> >                          (intmax_t)image_stat.st_size, size);
> > -               fclose(image);
> > -               return 1;
> > +               return -1;
> >         }
> > +       size = image_stat.st_size;
> >         numbytes = fread(buf, 1, size, image);
> >         if (fclose(image)) {
> >                 msg_gerr("Error: closing file \"%s\" failed: %s\n", filename, strerror(errno));
> > -               return 1;
> > +               return -1;
> >         }
> >         if (numbytes != size) {
> >                 msg_gerr("Error: Failed to read complete file. Got %ld bytes, "
> >                          "wanted %ld!\n", numbytes, size);
> > -               return 1;
> > +               return -1;
> >         }
> > -       return 0;
> > +       return size;
> >  #endif
> >  }
> >
> > @@ -1481,7 +1481,10 @@ static int walk_eraseregions(struct flashctx *flash, int erasefunction,
> >                  * members so the loop below won't be executed for them.
> >                  */
> >                 len = eraser.eraseblocks[i].size;
> > -               for (j = 0; j < eraser.eraseblocks[i].count; j++) {
> > +               for (j = 0;
> > +                    j < eraser.eraseblocks[i].count &&
> > +                    start + len <= flash->chip->total_size * 1024;
> > +                    j++) {
> >                         /* Print this for every block except the first one. */
> >                         if (i || j)
> >                                 msg_cdbg(", ");
> > @@ -1988,11 +1991,12 @@ int doit(struct flashctx *flash, int force, const char *filename, int read_it,
> >         }
> >
> >         if (write_it || verify_it) {
> > -               if (read_buf_from_file(newcontents, size, filename)) {
> > +               size = read_buf_from_file(newcontents, size, filename);
> > +               if (size < 0) {
> >                         ret = 1;
> >                         goto out;
> >                 }
> > -
> > +               flash->chip->total_size = size / 1024; /* FIXME */
> >  #if CONFIG_INTERNAL == 1
> >                 if (programmer == PROGRAMMER_INTERNAL && cb_check_image(newcontents, size) < 0) {
> >                         if (force_boardmismatch) {
> > --
> > 2.1.4
> >
> >
> > _______________________________________________
> > flashrom mailing list
> > flashrom at flashrom.org
> > https://www.flashrom.org/mailman/listinfo/flashrom
> 
> 
> 
> -- 
> David Hendricks (dhendrix)
> Systems Software Engineer, Google Inc.