Laszlo Ersek <[email protected]> writes:
> On 02/21/19 19:48, Alex Bennée wrote: >> It looks like there was going to be code to check we had some sort of >> alignment so lets replace it with an actual check. This is a bit more >> useful than the enigmatic "failed to read the initial flash content" >> when we attempt to read the number of bytes the device should have. >> >> This is a potential confusing stumbling block when you move from using >> -bios to using -drive if=pflash,file=blob,format=raw,readonly for >> loading your firmware code. To mitigate that we automatically pad in >> the read-only case. >> >> Signed-off-by: Alex Bennée <[email protected]> >> >> --- >> v3 >> - tweak commit title/commentary >> - use total_len instead of device_len for checks >> - if the device is read-only do the padding for them >> - accept baking_len > total_len (how to warn_report with NULL *errp?) >> --- >> hw/block/pflash_cfi01.c | 28 +++++++++++++++++++++------- >> 1 file changed, 21 insertions(+), 7 deletions(-) >> >> diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c >> index 00c2efd0d7..37d7513c45 100644 >> --- a/hw/block/pflash_cfi01.c >> +++ b/hw/block/pflash_cfi01.c >> @@ -714,13 +714,6 @@ static void pflash_cfi01_realize(DeviceState *dev, >> Error **errp) >> } >> device_len = sector_len_per_device * blocks_per_device; >> >> - /* XXX: to be fixed */ >> -#if 0 >> - if (total_len != (8 * 1024 * 1024) && total_len != (16 * 1024 * 1024) && >> - total_len != (32 * 1024 * 1024) && total_len != (64 * 1024 * 1024)) >> - return NULL; >> -#endif >> - >> memory_region_init_rom_device( >> &pfl->mem, OBJECT(dev), >> &pflash_cfi01_ops, >> @@ -747,6 +740,27 @@ static void pflash_cfi01_realize(DeviceState *dev, >> Error **errp) >> } >> >> if (pfl->blk) { >> + /* >> + * Validate the backing store is the right size for pflash >> + * devices. It should be padded to a multiple of the flash >> + * block size. If the device is read-only we can elide the >> + * check and just null pad the region first. If the user >> + * supplies a larger file we silently accept it. > > (1) I recommend adding "and ignore the tail". > >> + */ >> + uint64_t backing_len = blk_getlength(pfl->blk); > > (2) Didn't we intend to check for blk_getlength() errors (or assert that > there would be none)? Oops, yes I'll fix that. > >> + >> + if (backing_len < total_len) { >> + if (pfl->ro) { >> + memset(pfl->storage, 0, total_len); > > (3) Should we "optimize" (well, okay, de-pessimize) this to: > > memset((uint8_t*)pfl->storage + backing_len, 0, > total_len - backing_len); > > ? I mean in the grand scheme of things it's unlikely to show up in any benchmarks so I went for simple and easy to get right. > >> + total_len = backing_len; >> + } else { >> + error_setg(errp, "device(s) needs %" PRIu64 " bytes, " > > (4) not too important, I'm just curious: why the optional plural? I discovered the difference between device_len and total_len and found (for some reason) the efivars came out as multiple devices. > >> + "backing file provides only %" PRIu64 " bytes", >> + total_len, backing_len); >> + return; >> + } >> + } >> + >> /* read the initial flash content */ >> ret = blk_pread(pfl->blk, 0, pfl->storage, total_len); >> >> > > I don't feel too strongly about these, so if you disagree, I won't push. > > Thanks! > Laszlo -- Alex Bennée
