From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:53823) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h1pOu-00049O-Uy for qemu-devel@nongnu.org; Thu, 07 Mar 2019 04:33:17 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h1pOt-00025m-8G for qemu-devel@nongnu.org; Thu, 07 Mar 2019 04:33:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37980) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h1pOr-00024s-8d for qemu-devel@nongnu.org; Thu, 07 Mar 2019 04:33:13 -0500 From: Markus Armbruster References: <20190227111347.15063-1-alex.bennee@linaro.org> Date: Thu, 07 Mar 2019 10:33:09 +0100 In-Reply-To: <20190227111347.15063-1-alex.bennee@linaro.org> ("Alex =?utf-8?Q?Benn=C3=A9e=22's?= message of "Wed, 27 Feb 2019 11:13:47 +0000") Message-ID: <87wolbt4fe.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v5] hw/block: better reporting on pflash backing file mismatch List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex =?utf-8?Q?Benn=C3=A9e?= Cc: Laszlo Ersek , qemu-devel@nongnu.org One more thing... Alex Benn=C3=A9e writes: > 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=3Dpflash,file=3Dblob,format=3Draw,readonly for > loading your firmware code. To mitigate that we automatically pad in > the read-only case and warn the user when we have performed magic to > enable things to Just Work (tm). > > Signed-off-by: Alex Benn=C3=A9e > Reviewed-by: Laszlo Ersek > > --- > 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?) > v4 > - error check blk_getlength > - optimise memset and use NOR erase pattern > - restore singular device (overly confusing) > - add warn_report for when we do magic > v5 > - remove mention of null padding > - use %zu for size_t fmt string > - add Laszlo r-b > --- > hw/block/pflash_cfi01.c | 40 +++++++++++++++++++++++++++++++++------- > 1 file changed, 33 insertions(+), 7 deletions(-) > > diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c > index 9d1c356eb6..d8cfa4789a 100644 > --- a/hw/block/pflash_cfi01.c > +++ b/hw/block/pflash_cfi01.c > @@ -45,6 +45,7 @@ > #include "qemu/bitops.h" > #include "qemu/host-utils.h" > #include "qemu/log.h" > +#include "qemu/error-report.h" > #include "hw/sysbus.h" > #include "sysemu/sysemu.h" > #include "trace.h" > @@ -730,13 +731,6 @@ static void pflash_cfi01_realize(DeviceState *dev, E= rror **errp) > } > device_len =3D sector_len_per_device * blocks_per_device; >=20=20 > - /* XXX: to be fixed */ > -#if 0 > - if (total_len !=3D (8 * 1024 * 1024) && total_len !=3D (16 * 1024 * = 1024) && > - total_len !=3D (32 * 1024 * 1024) && total_len !=3D (64 * 1024 *= 1024)) > - return NULL; > -#endif > - > memory_region_init_rom_device( > &pfl->mem, OBJECT(dev), > &pflash_cfi01_ops, > @@ -763,6 +757,38 @@ static void pflash_cfi01_realize(DeviceState *dev, E= rror **errp) > } >=20=20 > 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 pad the region first. If the user supplies a > + * larger file we ignore the tail. > + */ I can't see how "It should be padded to a multiple of the flash block size" is related to the code you add. > + int64_t backing_len =3D blk_getlength(pfl->blk); > + if (backing_len < 0) { > + error_setg(errp, "unable to check size of backing file"); > + return; > + } > + > + if (backing_len < total_len) { > + if (pfl->ro) { > + size_t pad_bytes =3D total_len - backing_len; > + /* pad with NOR erase pattern */ > + memset((uint8_t*)pfl->storage + backing_len, 0xff, pad_b= ytes); > + warn_report("device needs %" PRIu64 > + " bytes, padded with %zu 0xff bytes", > + total_len, pad_bytes); > + total_len =3D backing_len; > + } else { > + error_setg(errp, "device needs %" PRIu64 " bytes, " > + "backing file provides only %" PRIu64 " bytes= ", > + total_len, backing_len); > + return; > + } > + } else if (backing_len > total_len) { > + warn_report("device needs %" PRIu64 " bytes, rest ignored", = total_len); > + } > + > /* read the initial flash content */ > ret =3D blk_pread(pfl->blk, 0, pfl->storage, total_len);